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  • Column liquid chromatography  (349)
  • hypertension  (146)
  • ASTROPHYSICS
  • Data analysis / ~ processing
  • Industrial Chemistry
  • Inorganic Chemistry
  • NOISE
  • Seismology
  • ddc:330
  • Springer  (500)
  • DGG  (3)
  • 1985-1989  (501)
  • 1950-1954  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Pharmacokinetics of ramipril in hypertensive patients with renal insufficiency (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 249-256 
    Details
    ISSN: 1432-1041
    Keywords: ramipril ; renal insufficiency ; hypertension ; pharmacokinetics ; ramiprilat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In an open trial, the pharmacokinetics of ramipril and its active metabolite ramiprilat were studied in 25 hypertensive patients with various degrees of renal insufficiency given 5 mg ramipril p.o. for 14 days. Ramipril was rapidly absorbed and reached a peak concentration after 1–2 h. Cmax was greater in patients with severe renal insufficiency, which might indicate a reduced renal elimination rate, although, the rapid decline of the concentration-time curve for ramipril was almost independent of renal function. The mean initial apparent half-lives on Days 1 and 12, respectively, were 2.8 and 3.4 h (Group I: creatinine clearance 5–15 ml/min), 1.8 and 2.3 h (Group II: creatinine clearance 15–40 ml/min), and 1.9 and 1.9 h (Group III: creatinine clearance 40–80 ml/min). No accumulation was observed after multiple dosing. In contrast, the kinetics of its active acid metabolite ramiprilat was significantly influenced by renal function. The mean times to the peak plasma concentration were 5.7 h in Group I, 4.4 h in Group II and 3.8 h in Group III. The initial decline in plasma ramiprilat was dependent upon renal function; the mean initial apparent half-lives (Days 1 and 12, respectively) were 16.0 and 14.8 h (Group I), 10.1 and 9.5 h (Group II) and 10.6 and 8.0 h (Group III). Mean trough concentrations and absolute accumulation also increased with worsening renal function, and the renal clearance of ramiprilat was significantly correlated with the creatinine clearance. The subsequent long terminal phase at low plasma ramiprilat concentrations represented slow dissociation of the ACE-inhibitor complex. The study indicates that in patients with severe renal insufficiency (creatinine clearance below 30 ml/min) smaller doses of ramipril are required than in patients with normal or borderline renal function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00679779
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  • 2
    Electronic Resource
    Electronic Resource
    Renal and hormonal effects of alpha1-adrenoceptor blockade by bunazosin in essential hypertension (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 575-578 
    Details
    ISSN: 1432-1041
    Keywords: bunazosin ; hypertension ; alpha1-adrenoceptor blocker ; blood pressure ; renal blood flow ; renal function ; renin ; aldosterone ; atrial natriuretic peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The renal and hormonal effects of the α1-adrenoceptor blocker bunazosin were examined in 6 patients with essential hypertension. Oral bunazosin for 4 to 12 weeks significantly decreased mean blood pressure by 10%, increased effective renal blood flow and creatinine clearance by 34% and 37%, respectively, the plasma norepinephrine concentration was elevated by 60%, and the plasma atrial natriuretic peptide level was lowered by 22%. The plasma renin activity and aldosterone concentration were unchanged. Thus, a moderate reduction in blood pressure was produced by bunazosin treatment while maintaining renal perfusion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00637738
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  • 3
    Electronic Resource
    Electronic Resource
    Haemodynamic effects and pharmacokinetics of felodipine at rest and during exercise in hypertensive patients treated with metoprolol or atenolol (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 459-465 
    Details
    ISSN: 1432-1041
    Keywords: felodipine ; metoprolol ; atenolol ; hypertension ; exercise ; pharmacokinetics ; adverse effects ; hypotensive action
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A study has been performed in thirteen patients with essential hypertension, WHO Class I–II, and a diastolic blood pressure ≥95 mm Hg, on beta-blocker (metoprolol or atenolol) monotherapy, who were also given felodipine 10 mg b.d. for 28 days. The acute and steady state blood pressure response at rest and during exercise, and the pharmacokinetics of felodipine and metoprolol, were examined. Felodipine in combination with the beta-blocker reduced the systolic and diastolic blood pressures acutely and at steady-state. The duration of the effect was longer at steady-state. There was a significant correlation between the plasma concentration of felodipine and the change in blood pressure. The increase in systolic blood pressure during exercise was of the same magnitude before and after felodipine administration. No change in resting supine heart rate was found after the administration of felodipine. There were no significant differences in the pharmacokinetics of felodipine during long-term treatment, except for the trough plasma concentration, which was increased at steady-state, even though cumulation of felodipine and its metabolite did not occur. There was a significant decrease in the maximal plasma concentration and AUC of metoprolol after 28 days of treatment with felodipine, but its elimination half-life was not changed. The adverse reactions reported during this study were those generally seen after dihydropyridines and, except for two patients who were withdrawn after the first study day, the effects were well tolerated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558124
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  • 4
    Electronic Resource
    Electronic Resource
    Enalapril and hydrochlorothiazide in hypertensive Africans (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 229-234 
    Details
    ISSN: 1432-1041
    Keywords: enalapril ; hydrochlorothiazide ; hypertension ; side-effects ; Africans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The antihypertensive efficacy both of angiotensin converting enzyme (ACE) inhibitors and thiazide diuretics has been claimed to be influenced by plasma renin activity, which declines with age and is low in blacks. In a double-blind, placebo-controlled, double-dummy, randomized, parallel-group preliminary study, the antihypertensive efficacy and tolerability of the ACE inhibitor enalapril (20 mg day−1) and hydrochlorothiazide (50 mg day−1) were evaluated and compared for 4 weeks in 20 African patients with essential hypertension. The two groups had similar baseline clinical features and serum Na+ and K+ levels. Hydrochlorothiazide caused a significant and sustained fall in erect blood pressure with a reflex tachycardia. Enalapril exerted only a modest antihypertensive action, but significantly reduced erect heart rate. Direct comparison of hydrochlorothiazide — and enalapril — induced hypotension suggested a greater fall in subjects on the thiazide. The 95% confidence limits for the thiazide-enalapril difference in antihypertensive action at the end of the study was 39.5 to −7.5 mm Hg systolic and 22.0 to −6.6 mm Hg diastolic. The maximal blood pressure fall after hydrochlorothiazide was positively correlated with age (r=0.50;p〈0.05), whilst that of enalapril was inversely related age to (r=−0.57,p〈0.05). The results are compatible with the notion that ACE inhibitor monotherapy may be less effective than thiazide diuretic treatment in African and black patients with essential hypertension. The findings also support the concept that age and racial factors may influence the response to antihypertensive treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558152
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  • 5
    Electronic Resource
    Electronic Resource
    Acute calcium entry blockade inhibits the blood pressure but not the hormonal responses to angiotensin II (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 567-573 
    Details
    ISSN: 1432-1041
    Keywords: isradipine ; hypertension ; blood pressure ; calcium entry blockade ; renin angiotensin system ; aldosterone plasma renin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of acute calcium entry blockade by isradipine (IS) and placebo (P) on the haemodynamic and humoral responses to angiotensin II (A II) have been compared in two groups of 9 patients with essential hypertension. During 4 sequential periods each of 20 min, an i.v. infusion of A II 0, 2, 4 and 8 ng · kg−1 · min−1 was given before (control) and 30 min after the oral administration either of IS or P. After IS, both the blood pressure and the angiotensin II-induced pressor effect were significantly reduced. Isradipine increased the heart rate and this cardio-acceleration was potentiated by A II. In contrast, when A II was infused in the absence of IS, heart rate tended to decrease. IS stimulated plasma renin activity and reduced plasma aldosterone. However, it did not affect either the inhibition of plasma renin activity or the rise in plasma aldosterone in response to A II. In conclusion, acute calcium entry blockade in patients with essential hypertension reduces the pressor response to A II, but not the A II-induced inhibition of renin and increase in plasma aldosterone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00637737
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  • 6
    Electronic Resource
    Electronic Resource
    Ambulatory blood pressure monitoring during sustained treatment with conventional and extended-release felodipine in mild-to-moderate hypertension (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 555-557 
    Details
    ISSN: 1432-1041
    Keywords: felodipine ; hypertension ; ambulatory blood pressure monitoring ; slow-release formulation ; side-effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To assess the duration of the antihypertensive effect of the dihydropiridine calcium antagonist felodipine in conventional (C-F) and slow-release (ER-F) formulations, 12 patients with essential hypertension underwent ambulatory blood pressure monitoring (ABPM) at the end of a 2-week treatment period with C-F 5 mg b.d., ER-F 10 mg once daily (o.d.) and placebo. C-F, ER-F and placebo were given in a double-blind 3×3 latin square design 4 times replicated. There was no systematic change in the ABP profile over the three study periods regardless of the treatment. In comparison to placebo, the mean 24-h systolic and diastolic blood pressures showed a significant and similar reduction after both formulations of F. Compared to placebo, C-F and ER-F induced a significant reduction in systolic blood pressure for 15 and 21 h, respectively, and of diastolic blood pressure for 16 and 21 h, respectively. Three patients complained of headache (mild in 2, moderately severe in 1), and two patients of nocturia, with either formulation of F.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00562543
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of nicardipine on insulin secretion, glucose and lipid metabolism in hypertensive, non-insulin dependent diabetics (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 1-4 
    Details
    ISSN: 1432-1041
    Keywords: nicardipine ; insulin ; glucose ; diabetes ; hypertension ; metabolic effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Certain acute and chronic metabolic effects of nicardipine have been studied in 20 patients with non-insulin dependent diabetes (NIDD). An intravenous glucose tolerance test (i.v. GTT, glucose 0.33 g/kg as a bolus) and the corresponding insulin response were assessed at the end of a 4 week placebo period, after the first dose and on administration for 12 weeks of nicardipine 20 mg t.i.d. The glucose and insulin responses to the i.v. GTT, evaluated as incremental AUCs, did not change significantly (glucose 30.5 mg/dl·90 min on placebo, 33.1 mg/dl·90 min acutely and 31.4 mg/dl·90 min on chronic administration of nicardipine; insulin 2.08 µU/ml·90 min on placebo, 1.87 µU/ml·90 min acutely and 1.93 µU/ml·90 min after chronic nicardipine). Glucose removal rate (KG) following the i.v. GTT was 0.73%/min on placebo 0.75%/min on acute administration and 0.8%. min−1 with chronic nicardipine. Active treatment produced a significant reduction of blood pressure (from 187/96 mm Hg on placebo to 166/89 mm Hg acutely and 152/83 mm Hg after 12 weeks of nicardipine treatment). It is concluded that the calcium antagonist nicardipine was an effective antihypertensive drug, and that it did not cause deterioration of metabolic control in hypertensive patients with NIDD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00561014
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  • 8
    Electronic Resource
    Electronic Resource
    Is captopril effective in controlling blood pressure when administered once daily? An assessment using 24-h ambulatory blood pressure monitoring (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 11-15 
    Details
    ISSN: 1432-1041
    Keywords: hypertension ; captopril ; once-daily administration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Twelve patients with essential hypertension receiving captopril monotherapy or captopril in conjunction with a diuretic had their 24-h blood pressure profiles monitored using an automatic, non-invasive ambulatory method. The study examined the efficacy of once a day versus twice a day administration of the ACE inhibitor in controlling blood pressure. Six untreated subjects with borderline hypertension were also studied using the same monitoring equipment and with the same frequency, to act as controls because of the possibility of repeated use of the device causing a ‘familiarisation’ effect. The results obtained indicated that if anything, the once daily dosing produced marginally better blood pressure values. The amplitude of the diurnal blood pressure variation was reduced on a ‘second-wearing’ of the monitoring equipment suggesting some degree of familiarisation with the apparatus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00561016
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of carteolol on renal function in healthy subjects and patients with hypertension (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 83-86 
    Details
    ISSN: 1432-1041
    Keywords: carteolol ; hypertension ; chronic renal failure ; renal function
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of short- and long-term administration of carteolol on renal function has been examined in healthy subjects and in hypertensive patients with or without renal failure. In healthy subjects neither a single dose of 10 mg carteolol nor continuous administration of 20 mg/day for 7 days had any effect on creatinine clearance and renal blood flow. In all subjects the clearance rate of carteolol was about 400 ml/min and its fractional excretion of carteolol exceeded 300%, suggesting that the drug is secreted actively from renal tubules. Twenty-three hypertensive patients with or without renal dysfunction were given carteolol 10 to 20 mg/day for more than 50 weeks in addition to their standard antihypertensive regimens, which were left changed. Laboratory results were compared with the mean values of 50 weeks before and after the addition of carteolol, and none, including plasma creatinine, blood urea nitrogen and electrolytes, were significantly changed. Neither the estimated glomerular filtration rate nor the effect of the drug on blood pressure changed significantly during this prolonged treatment. It is concluded that carteolol had no effect on renal function in healthy subjects and in hypertensive patients with or without renal failure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00561030
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  • 10
    Electronic Resource
    Electronic Resource
    Cardiovascular regulation and lipoprotein profile during administration of co-dergocrine in essential hypertension (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 119-125 
    Details
    ISSN: 1432-1041
    Keywords: co-dergocrine ; hypertension ; presynaptic dopamine2-receptors ; norepinephrine ; haemodynamic effects ; side-effects ; renin-angiotensin-aldosterone system ; lipoproteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Co-dergocrine has recently been demonstrated acutely to lower plasma norepinephrine (NE) and blood pressure (BP) in patients with essential hypertension, and similar results have been obtained during chronic administration of co-dergocrine to healthy men. The present study investigated the effect of 3 weeks of treatment with co-dergocrine 4 mg/day on BP, plasma catecholamines, certain other BP-regulating factors and serum lipoproteins in patients with essential hypertension. Compared to placebo conditions, co-dergocrine decreased supine BP and heart rate by −7% and the upright plasma NE level by −24%. Supine plasma NE also fell (−24%). Total cholesterol and the LDL + VLDL-cholesterol lipoprotein fraction were lowered by −6%. No significant change was observed in plasma renin activity, angiotensin II, aldosterone and epinephrine levels, whole blood and plasma volume, exchangeable sodium, and the cardiovascular responsiveness to NE, angiotensin II and isoproterenol. The findings suggest that in patients with essential hypertension, chronic treatment with co-dergocrine may slightly decrease sympathetic outflow and, at least in the short-term, lower the potentially atherogenic serum LDL + VLDL − cholesterol fraction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00609182
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  • 11
    Electronic Resource
    Electronic Resource
    Antihypertensive and hypouricaemic effects of nitrendipine in chronic renal failure (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 223-227 
    Details
    ISSN: 1432-1041
    Keywords: nitrendipine ; renal failure ; hypertension ; uric acid excretion ; metabolic effects ; cardiovascular risk factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary To evaluate the potential therapeutic value of calcium antagonists in hypertension associated with impaired renal function, blood pressure (BP), certain regulatory factors, and metabolic correlates of cardiovascular risk have been assessed in 15 patients with mild to marked chronic renal failure before and after 6 weeks of therapy with nitrendipine. Compared to placebo, nitrendipine (mean final dose 55 mg/day) decreased supine BP from 173/102 to 146/81 mm Hg and upright BP from 170/105 to 145/86 mm Hg. Heart rate, body weight (+0.8 kg) and exchangeable sodium (+176 mmol, not significant) were minimally increased, and plasma and whole blood volume, plasma angiotensin II and creatinine concentrations, and urinary electrolyte and creatinine excretion were not significantly changed. Nitrendipine increased uric acid excretion and lowered plasma uric acid by 24%; glucose, insulin, serum total lipids, and lipoprotein fractions were unchanged.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558151
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  • 12
    Electronic Resource
    Electronic Resource
    Responses of glomerular filtration, renal blood flow and salt-water handling to acute cardioselective and non-selective β-adrenoceptor blockade in essential hypertension (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 343-345 
    Details
    ISSN: 1432-1041
    Keywords: metoprolol ; pindolol ; renal haemodynamics ; salt-water handling ; hypertension ; beta-adrenoceptor blockade ; ISA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects on renal hemodynamics and salt-water handling of equipotent doses of the cardioselective β-blocker metoprolol (M, 100 mg) and of the non-selective (intrinsic sympathetic activity) β-antagonist pindolol (P, 10 mg) were compared in 30 WHO Grade 1–2 hypertensive men. M lowered pulse rate more than P. Systolic pressure was equally reduced by both agents, and diastolic and mean pressures were decreased only after P. Glomerular filtration rate was not significantly altered by either antagonist, and renal blood flow decreased by approximately 11% both after M and P. Renal vascular resistance was unchanged after P, and was increased by 10% after M. It is concluded that, like the effects on central haemodynamics, ISA is more important in the renal response to β-adrenoceptor blockade than is β-receptor selectivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558292
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  • 13
    Electronic Resource
    Electronic Resource
    Long-term effect of pindolol on lipids and lipoproteins in men with newly diagnosed hypertension (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 347-350 
    Details
    ISSN: 1432-1041
    Keywords: pindolol ; hypertension ; hyperlipidaemia ; chronic treatment ; cholesterol ; HDL ; LDL ; triglycerides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary This is the first long-term study of pindolol in a population-based sample of men with newly diagnosed hypertension. Eighty-two patients, with a diastolic pressure of 100 mm Hg or more, were identified after screening 6000 men. Many patients were overweight. 82 population controls, matched by sex, age and body mass index, were also recruited. Fourty-eight per cent of the patients and 25% of the controls had a family history of hypertension. Serum triglyceride and urate values were higher in patients than controls at the baseline investigation. Seventy-four patients were followed for 1 year. The dose of pindolol averaged 7.7 mg once daily after 1 year. The diastolic blood pressure was reduced by 13.4 mm Hg. The target pressure of 95 mm Hg or less was achieved in 89% of the patients. The HDL-cholesterol concentration was normal and did not change, whereas the LDL-cholesterol concentration decreased by 0.15 mmol · l−1 during treatment. The total triglyceride values increased transiently up to 6 months, but no significant increase was seen after one year. It is concluded that pindolol had no adverse effect on serum cholesterol and its HDL- and LDL-fractions during 1 year of treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558293
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  • 14
    Electronic Resource
    Electronic Resource
    Antihypertensive effect of slow-release nicardipine. A placebo-controlled cross-over study (1989)
    Springer
    European journal of clinical pharmacology 36 (1989), S. 439-442 
    Details
    ISSN: 1432-1041
    Keywords: calcium antagonists ; nicardipine ; hypertension ; placebo effect ; slow-release preparation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The magnitude and duration of the anti-hypertensive effect of slow-release nicardipine (SR-Nicardipine) have been compared with placebo in 36 uncomplicated essential hypertensives (diastolic BP 95 to 115 mm Hg after 1-month placebo washout). According to a double-blind, randomized, cross-over design they received SR-Nicardipine 40 mg b.d. and placebo for 1 month. At the end of each treatment period, blood pressure and heart rate were measured 12 h after the evening dose and 1, 2, 3 and 4 h after the morning dose. SR-Nicardipine significantly reduced systolic (SBP) and diastolic (DBP) blood pressure at each time after dosing. The absolute decrements peaked 4 h after dosing (−18.3 and −11.7 mm Hg, respectively) and more than 90% of the peak effect persisted 12 h after dosing, both for SBP and DBP. The heart rate was slightly increased by SR-Nicardipine. Adverse effects monitored with a check-list occurred in 31% of patients during SR-Nicardipine treatment and in 28% on placebo. Thus, SR-Nicardipine 40 mg b.d. has a maintained and significant antihypertensive effect lasting up to 12 h in essential hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558066
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  • 15
    Electronic Resource
    Electronic Resource
    Dependent oedema and attenuation of postural vasoconstriction associated with nifedipine therapy for hypertension in diabetic patients (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 333-335 
    Details
    ISSN: 1432-1041
    Keywords: diabetes mellitus ; nifedipine ; hypertension ; oedema ; vasodilator ; blood flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary We studied the incidence of oedema 2 weeks following initation of nifedipine therapy for hypertension in a group of 10 diabetic subjects, and also measured skin blood flow (SBF) with a laser Doppler flowmeter, before and after lowering the foot. SBF with the foot horizontal increased after nifedipine from 0.31V (arbitrary units of flow) to 0.51V (NS). The postural fall in blood flow in dependency was significantly attenuated by nifedipine from 64.4 to 24.0%. Five patients developed ankle oedema. Results were similar in a small group of non-diabetic subjects starting nifedipine. The attenuation of reflex postural vasoconstriction is therefore likely to contribute to development of the oedema associated with starting nifedipine therapy, which should be monitored carefully in diabetic patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558495
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  • 16
    Electronic Resource
    Electronic Resource
    Comparative haemodynamic effects of ketanserin and ritanserin in the proximal and distal upper limb circulations of hypertensive patients (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 215-220 
    Details
    ISSN: 1432-1041
    Keywords: ketanserin ; ritanserin ; hypertension ; haemodynamics ; alpha1-adrenoceptor blockade
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effects of ketanserin (40 mg p.o.) on blood pressure and brachial haemodynamics (brachial artery diameter, brachial blood velocity and blood flow) have been compared in a double-blind study with those of ritanserin (10 mg p.o.) and placebo. Haemodynamic parameters were measured before and 1 h after treatment. Patients with mild to moderate essential hypertension participated in this study, 6 each on ketanserin, ritanserin and placebo. Placebo significantly reduced heart rate and did not modify the other parameters. Compared to placebo, ketanserin significantly reduced systolic and diastolic blood pressure, increased brachial blood velocity and flow, and decreased forearm vascular resistance. Compared to placebo, ritanserin slightly decreased blood pressure and slightly increased blood flow, but neither effect was significant. When blood circulation to the hand was excluded, neither ketanserin nor ritanserin modified the proximal arterial resistance or blood flow. It is concluded that the actions of ketanserin and ritanserin essentially occurred in the distal part of the upper limb, and alpha1-receptor blockade is probably involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00679772
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  • 17
    Electronic Resource
    Electronic Resource
    The effect of nisoldipine on renal function in the long-term treatment of hypertension in patients with and without renal impairment (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 437-441 
    Details
    ISSN: 1432-1041
    Keywords: nisoldipine ; hypertension ; renal function/-impairment ; calcium antagonist
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The effect of nisoldipine on renal function after 6 weeks treatment was investigated in hypertensive patients with and without renal impairment. Nisoldipine was well tolerated and an effective antihypertensive agent when administered over a period of 6 weeks. There were no significant changes in glomerular filtration, cardiac output, plasma renin activity or serum biochemistry during nisoldipine administration. Effective renal plasma flow was unaffected by treatment in the patients with normal renal function, but in the patients with renal insufficiency, the value decreased by a mean of 12%. Nisoldipine had no major untoward effects on renal function after 6 weeks administration, but minor changes in renal haemodynamics in the patients with renal insufficiency would suggest that careful monitoring of renal function is indicated in such patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00558120
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  • 18
    Electronic Resource
    Electronic Resource
    Once daily nisoldipine in hypertension: cuff and ambulatory intra-arterial blood pressure (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 551-554 
    Details
    ISSN: 1432-1041
    Keywords: nisoldipine ; hypertension ; ambulatory monitoring ; cuff blood pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Cuff blood pressure data has suggested that the calcium channel antagonist nisoldipine has full twenty four hour efficacy. To test this, 24 h ambulatory intra-arterial blood pressure monitoring was performed on 18 untreated hypertensive subjects (12 men, 6 women) (cuff blood pressure 〉150/95 mm Hg) before and after chronic treatment with 10–20 mg oral nisoldipine taken daily at 08.00 h. Twelve patients completed the study, six being withdrawn, four because of side-effects. After baseline intra-arterial monitoring patients were started on 10 mg nisoldipine daily. Response was assessed by cuff pressures taken 24 h after dosing at fortnightly intervals, and if not controlled (〈150/95 or at least 10 mm Hg reduction in diastolic BP) the dose was increased to 20 mg. All patients received at least six weeks' therapy before the second intra-arterial blood pressure monitoring. There was a slight but insignificant reduction in mean daytime heart rate of 3 beats·min−1. Mean significant reduction in daytime systolic and diastolic BP was 19 mm Hg and 13 mm Hg respectively but there was no significant mean night-time reduction. By comparison 8 out of 12 patients were apparently controlled more than 24 h post dose according to cuff pressures. This study suggests that this formulation of nisoldipine does not control blood pressure over a full 24-h period, and emphasises the importance of 24 h ambulatory monitoring in assessing the efficacy of once-daily antihypertensive agents.
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    URL: http://dx.doi.org/10.1007/BF00562542
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    Membrane transport and disease (1989)
    Springer
    Molecular and cellular biochemistry 91 (1989), S. 3-11 
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    ISSN: 1573-4919
    Keywords: calcium ATPase ; glucose transport ; herpes virus ; hypertension ; leaks ; pore-formation ; sodium channels ; stress ; toxins ; transport ; viruses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Four situations in which membrane transport is altered by disease are discussed: (a) non-specific leaks induced by poreforming agents; (b) glucose transport and cellular stress; (c) Ca+-ATPase and hypertension; (d) Na− channels and HSV infection.
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    URL: http://dx.doi.org/10.1007/BF00228073
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    RPLC retention of 1,ω-di(alkoxy)-polysulphides (1989)
    Springer
    Chromatographia 27 (1989), S. 27-30 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; 1,ω-Di(alkoxy)-polysulphides ; Retention contributions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reaction of S2Cl2 with alcohols yields products, the reversed-phase liquid chromatograms of which are similar to those of dialkyl-polysulphides RSnR, i.e., they represent homologous series. Four of the products were identified via GC-MS as 1,ω-di(alkoxy)-polysulphides having the general structure ROSnOR. Retention contributions of alkyl groups R and sulphur atoms in the −Sn — chain are not much different from values observed with polysulphides. The effect of oxygen, however, is only about −100 index units per O atom, while in dialkyl ethers values of −500 units have been reported.
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    URL: http://dx.doi.org/10.1007/BF02290400
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    A practical description of retention in reversed phase chromatography using four parameters (1989)
    Springer
    Chromatographia 27 (1989), S. 5-14 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention behaviour ; Column parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Retention of small molecules on reversed phase or other hydrophobic stationary phases can be represented by k′ values of members of a homologous series at varying solvent compositions. The evaluation of simple linear relationships leads to the introduction of a set of four parameters that contain all the information about retention behaviour of this homologous series in the binary solvent system chosen. It is possible to extrapolate to a hypothetical non-hydrophobic molecule and a solvent, the polarity of which equals that of the stationary phase, to characterize the properties of the stationary phase — eluent system. In addition, a chromatographic method for determination of the phase ratio of the column is proposed.
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    URL: http://dx.doi.org/10.1007/BF02290396
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    Purification of human chorionic gonadotropin hormone by anion-exchange high-performance liquid chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 601-604 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion exchange separation ; Preparative separations ; Human chorionic gonadotropin hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatography (HPLC) method was developed for the purification of 50mg crude human chorionic gonadotropin (HCG) hormone sample in one chromatographic run on a 250×10 mm SERVA DEAE Poliol-Si-500 column. During the 60-minute linear gradient of 0.05 M sodium sulfate, 0.05 M sodium hydrogen sulfate and 0.05% (v/v) acetonitrile in buffer “B” complete separation was accomplished in 40 min. Identity and purity of the fractions were checked by SDS electrophoretic method. The eluted HCG fractions were dialyzed for 24 hours to remove the buffer salts and liophilized. The activity of the hormone did not decreased significantly during the purification procedure.
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    Hemodynamics in emotional responses and in emotional stress (1989)
    Springer
    Neuroscience and behavioral physiology 19 (1989), S. 399-407 
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    ISSN: 1573-899X
    Keywords: hemodynamics ; stress ; hypertension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In the article, we present experimental data indicating that negative emotional states evoked by electrical stimulation of the ventromedial hypothalamus or by behavioral conflicts are accompanied by a predominance of vascular responses of a presser character possessing the property of summation. In contrast, positive emotional states during a self-stimulation reaction or when animals attain behavioral results satisfying their major biological demands are accompanied by a predominance of pressor-depressor vascular reactions. In individual animals under conditions of experimental emotional stress in conflicting situations of a prolonged character, pronounced disturbances of cardiac-vascular functions occur. Predominantly pressor vascular reactions arise in response to forced stimulation of the ventromedial hypothalamus in such cases. It is shown that changes in vascular tonus plays a leading role in disturbances of AP regulation during stress of immobilization. The most frequent cause of death in animals under such conditions is a progressive fall of AP due to an abrupt decrease in the total peripheral resistance. The resistance of the cardiac-vascular functions to emotional stress is determined to a significant degree by genetic mechanisms.
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    URL: http://dx.doi.org/10.1007/BF01197872
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    Energy calculations and computer modeling of chromatographic separations on microcrystalline cellulose triacetate (1989)
    Springer
    Chromatographia 27 (1989), S. 77-81 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microcrystalline cellulose triacetate ; Molecular modeling ; Computer graphics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Molecular modeling and energy calculations have been used to study the chromatographic separation of aromatic compounds on microcrystalline cellubose triacetate. A linear relationship has been found between the logarithms of the capacity factors and the energy values of the interaction of these compounds with this stationary phase. The interaction energies have been calculated for two different spatial dispositions of the solutes in relation to the sorbent.
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    A chemically bonded liquid crystal as a stationary phase for high performance liquid chromatography. Synthesis on silica via an organochlorosilane pathway (1989)
    Springer
    Chromatographia 27 (1989), S. 559-564 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Liquid crystals ; Synthesis of new bonded phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A compound which becomes a liquid crystal when bonded to a polysiloxane was reacted with dimethylchlorosilane to produce a reagent suitable for bonding to a silica surface. After the silanization reaction was complete, the product was characterized by elemental analysis, diffuse reflectance Fourier transform Infrared Spectroscopy (DRIFT), CP/MAS carbon-13 NMR and differential scanning calorimetry (DSC). Preliminary chromatographic testing was done by retention index measurements using the alkylarylketone homologous series and by measuring the separation factor, α, for anthracene/phenanthrene at two different mobile phase compositions.
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    Physico-chemical applications of HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 633-638 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Adsorption isotherms ; Equilibria criteria ; Silica and carbon adsorbents ; Aromatic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Examples of high-performance liquid chromatography (HPLC) are given for the determination of adsorption equilibrium and distribution coefficients, calculation of excess adsorption isotherms from solutions ranging from 10−7 to 10−1 mole fraction, changes in activity coefficient of the component predominantly adsorbed from solution and substitution enthalpy. These examples stem from studies of HPLC and the static adsorption of benzene, anisole and benzaldehyde from solutions in n-heptane on macroporous silica and active carbon at various temperatures. A criterion is suggested for evaluating equilibrium in the HPLC process. The potential of size-exclusion chromatography (SEC) for evaluating the volume and predominant diameter of adsorbed pores as well as pore diffraction are discussed. Prospects for HPLC application to molecularstructural analysis and other purposes are discussed briefly.
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    The use of large polycyclic aromatic hydrocarbons to study retention in non-aqueous reversed-phase HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 118-122 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase chromatography ; Non-aqueous reversed-phase chromatography ; Polycyclic aromatic hydrocarbons ; Solvent strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Elution strengths of 11 common HPLC solvents on a polymeric C18 phase were compared using a marker set of polycyclic aromatic hydrocarbons. Naphthalene, pyrene, benzo[ghi]perylene, and three larger naphthologues of 8, 10, and 12 rings (constituting a “naphthalene zigzag” series) were chosen because they span the solvent strength range up to and including the strongest solvents, tetrahydrofuran (THF) and chlorobenzene. Four pairs of similarly shaped isomers were used to probe solvent selectivity. With the exception of THF, HPLC solvent strength correlated with observed red shifts of fluorescence band maxima in each solvent. For THF, the pure solvent and blended mixtures behaved quite differently.
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    The case of the elusive tm values in HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 156-158 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mobile phase retention time ; Capacity factor ; Negative capacity factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Numerous ideas and procedures have been suggested in the literature for the determination of tm, the retention time of a non-retained species, in high-performance liquid chromatography. In some cases chromatograms have been obtained showing sample components eluting prior to the assumed non-retained species. This phenomenon results in apparent negative capacity factors for the species in question. We have proposed a method employing small inorganic anions which results in a limiting value for tm and eliminates apparent negative capacity factors.
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    Equilibrium structures of the Arg-aldehyde moiety upon HPLC of peptides (1989)
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    Chromatographia 27 (1989), S. 228-232 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase ; 13C n.m.r. ; Arginine-aldehyde peptides ; GYKI-14166
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatographic and13C n.m.r. spectrometry methods were used for the investigation of peptides containing arginine-aldehyde moiety. Investigation of a model compound, N-benzoyl-Arg-H, showed that in an acidic mobile phase peptides containing the arginine-aldehyde group elute in three characteristic peaks. The components of the peaks were found to be constituents of an equilibrium mixture. The structures of the two components were identified, one as the aldehyde hydrate, the other as the cyclanol derivative. The reactivity of TRIS (HCl) buffer at pH 8.5 with the arginine aldehyde moiety was used for the assignment of the equilibrium structures.
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    Ion-pair reversed phase HPLC determination of nucleotides, nucleosides and nucleobases — Application to nucleotide metabolism in hepatocytes (1989)
    Springer
    Chromatographia 27 (1989), S. 639-643 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase ; Ion-pair ; Recoveries ; Hepatocytes ; Purine compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three groups of metabolites were analyzed in extracts of rat hepatocytes by an HPLC method: (i) nucleotides (ATP, ADP, AMP, GTP, GDP, UTP, UDP, IMP, UMP), (ii) nucleosides and nucleobases (adenosine, adenine, guanosine, inosine, xanthine, hypoxanthine, uridine) and (iii) inhibitors of xanthine oxidoreductase (oxypurinol, allopurinol). Perchloric acid extracts were neutralized with K2CO3/triethanolamine and analyzed at 254 nm by reversed-phase ion-pair high-performance liquid chromatography. The nucleotides and their derivatives were separated with a gradient elution using 10 mM NH4H2PO4/2 mM t-butylammonium-phosphate and acetonitrile. Recovery values were estimated for the extraction procedure used. The method was applied to the investigation of nucleotide metabolism of hepatocytes of starved rats at anoxia and reoxygenation.
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    Preparation of silica-based cation-exchangers for use in ion chromatography (1989)
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    Chromatographia 27 (1989), S. 316-320 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Silica-based cation-exchanger ; Trimethylsilyl chlorosulfonate ; Lanthanides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A low exchange-capacity, silica-based cation-exchanger for use in ion chromatography has been synthesized. (p-Trimethylsilyl)benzyl-dimethylchlorosilane (TBDCS) reacts with trimethylsilyl chlorosulfonate (TMCS) to produce a compound sulfonated in the para position of the type ArSO2OSi (CH3)3, which is bonded to 5 μm porous silica beads and hydrolysed to the corresponding arylsulfonic acid. The product is hydrophilic and has a high degree of sulfonation, efficiencies of packed columns reaching about 40,000–50,000 plates per meter for the separation of the Mn2+ ion. The new stationary phase has been applied to the ion chromatography of some organic and inorganic ions. It is notable that 14 lanthanides can be separated by isocratic elution about one hour on a 150×4·6 mm column, with 4 mM ethylenediamine and 6 mM α-hydroxyl-isobutanoic acid (pH 3.67) as mobile phase.
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    Enhanced chemiluminescence detection of some dansyl amino acids in liquid chromatography (1989)
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    Chromatographia 27 (1989), S. 191-193 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dansyl amino acids ; Chemiluminescence ; Bis(2,4,6-Trichlorophenyl)oxalate, (TCPO) ; Enhancement of luminescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The dansylated amino acids alanine, glutamic acid, methionine and norleucine were separated by reversedphase HPLC and detected via chemical excitation using the post-column, TCPO-peroxyoxalate reaction system. Enhancement of the chemiluminescence emission was achieved by including the surfactant Triton X-100 in the eluent.
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    Measurement of elastin hydrolysis by reverse-phase HPLC with on-line post-colum derivatization (1989)
    Springer
    Chromatographia 27 (1989), S. 225-227 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reverse-phase chromatography ; Elastin Hydrolysis measurement ; On-line post-column derivatization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Excessive breakdown of elastin, a structural protein, may be related to aortic disease and emphysema. Since L-valyl-L-proline occurs in high concentrations in elastin, a rapid and sensitive method using HPLC with post-column on-line derivatization was used to measure the dipeptide from swine aortic tissue, and the amount of elastin present was determined. Elastin was extracted by alkaline hydrolysis. After neutralization and filtration, the sample was injected onto a ODS-2 gel column, and the dipeptide was eluted by a linear gradient of 0 to 10% of 1-propanol in 50 mM heptafluorobutyrate, pH 3, at a flow rate of 1 ml/min. The eluent was reacted with fluorescamine at pH 8.6, and fluorescence was detected at an excitation wavelength of 395 nm and a 455 nm cutoff emission filter.
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    Separation and purification of porcine pancreatic enzymes by serial operation of ion-exchange and affinity columns (1989)
    Springer
    Chromatographia 27 (1989), S. 449-454 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion exchange and affinity columns in series ; Porcine pancreatic enzymes ; Trypsin and elastase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to separate and purify some of the enzymes contained in porcine pancreas, operation of an ion-exchange column in series with an affinity column has been used. The enzymes dealt with possess very similar molecular weights, isoelectric points and active sites. Hence they are difficult to separate and purify by traditional separation and/or purification methods. CM-Sepharose anion-exchange resin adsorbs elastase and trypsin at low pH (4.5) and desorbs them at high pH (9.0) and high ionic strength. Chitin-CHOM affinity adsorbent adsorbs trypsin at high pH (8.0) and desorbs it at low pH (2.5). By virtue of this complementary relationship two chromatographic columns were connected in series for facilitating the separation and purification of elastase and trypsin from porcine pancreas. The result showed that the specific activities of elastase and trypsin had been increased 16 and 22 fold respectively.
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    Anion exchange behaviour of hydrous titanium oxide and its use for column separations (1989)
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    Chromatographia 27 (1989), S. 472-474 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Hydrous titanium oxide ; Anion exchange ; Polyvalent anions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Hydrous titanium oxide (HTiO), prepared under varying conditions of precipitation, has been studied for its anion exchange behaviour. Its chemical and thermal stability has been examined. The stoichiometry of uptake for Cl− has been investigated using a36Cl radiotracer and the regeneration power of the exchanger checked. Distribution coefficients for halides and polyvalent anions have been determined and on the basis of sorption data some polyvalent anions have been separated using HTiO columns.
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    An improved HPLC determination of flavonoids in medicinal plant extracts (1989)
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    Chromatographia 27 (1989), S. 509-512 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flavonoids ; Crataegus ; Passiflora ; Matricaria ; Ginkgo
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Flavonoids of Crataegus monogyna, Passiflora incarnata, Matricaria chamomilla and Ginkgo biloba extracts have been separated by isocratic elution on C18 columns using eluents based on C3 alcohols, tetrahydrofuran or dioxane. Satisfactory results have been obtained at compared to the low resolution achieved with the customary system acetonitrile-water-acetic acid.
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    Polymer coated stationary phases for liquid chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 19-23 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparation of stationary phases ; Polymer coated stationary phases ; Polymer-octyl bonded phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polymethyloctylsiloxane-coated stationary phases have been prepared for liquid chromatography, by thermal reaction. The influence of the reaction conditions on retention and efficiency of test substances with different structures has been discussed. The materials have good stability in both acidic and basic eluents.
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    Chromatography based on membrane separation with vesicular packing material (1989)
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    Chromatographia 28 (1989), S. 561-564 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size exclusion ; Vesicular packing material ; Proteins and polymers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new vesicular packing material — prepared from plant cell clusters by purification of the intact cell wall framework —is suitable for chromatography, giving high performance at low pressure gradients. The separation is achieved by dialysis through the cell wall, which is an ultrafilter membrane with an extremely sharp size limit of separation. Almost the whole of the stationary liquid phase is located within the vesicle (empty cell) lumina. In contrast to gel filtration vesicle chromatography gives a practically ideal separation of two size groups with an extremely short fractionation range. The size limit of separation was investigated by chromatography of proteins and other polymers. Group separation of molecules of a polydisperse dextran standard preparation showed that the critical Stokes' diameter for dextran permeation into the stationary liquid phase of the vesicular packing is 5 to 6 nm.
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    Semi-preparative high-performance liquid chromatographic separation of four 1.1-dimethylethyl 4- and 5-bromo-trans-2-methylcyclohexane-1-carboxylate isomers (1989)
    Springer
    Chromatographia 28 (1989), S. 585-587 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Preparative scale separation ; 1,1-Dimethylethyl 4- and 5-bromo-trans-2-methylcyclohexane-1-carboxylate ; Trimedlure-related isomers ; Ceratitis capitata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A semi-preparative high-performance liquid chromatographic procedure on 5-μm silica was developed for the isolation of gram quantities of four 1,1-dimethylethyl 4- and 5-bromo-trans-2-methylcyclohexane-1-carboxylate isomers (trimedlure-related) for NMR studies and comparative biological evaluation as male medfly,Ceratitis capitata, attractants.
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    Simultaneous determination of pseudouridine and creatinine in urine by HPLC with polarographic detection (1989)
    Springer
    Chromatographia 28 (1989), S. 605-609 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detection ; Pseudouridine ; Creatinine ; Urine analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The anodic behaviour of pseudouridine a modified nucleoside proposed as tumoral marker, has been studied at a mercury electrode. A method for its determination in urine samples by liquid chromatography with indirect anodic polarographic detection has been developed. The method is simple, highly selective and permits the direct injection of urine after dilution (1∶20) with mobile phase. Creatinine, which also gave an anodic response on mercury, could be simultaneously determined and used as an “internal standard” for Psi. This allowed the pseudouridine/creatinine ratio determination in a single run on the same specimen and the use of urine samples collected randomly instead of the 24h collection. The within-day RSD% for pseudouridine/ creatinine peak areas ratio was 3.4%.
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    Investigations into the chromatographic behaviour of silica gels produced from ester silicates (1989)
    Springer
    Chromatographia 28 (1989), S. 9-14 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ester silicate silica gels ; Behaviour with organic bases ; Silanol groups ; Acidic centres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Silica gels produced from ester silicates (ES-gels) are excellent chromatographic supports. In comparison with other silica gels the RP-materials obtained from them show little peak tailing even with polar, and, in particular, with basic compounds. Gels produced by various manufacturing processes have been classified by adsorption with methyl pyridinium chloride. ES-gels yield very low methyl pyridinium chloride values and small asymmetry parameters. The results indicate that there are strongly acidic, structurally-related surface centres which cause peak tailing on most commercial gels. It was shown that surface silanols on silica gels do not, in themselves, lead to peak tailing.
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    Analysis of preservatives in cosmetics—Methylisothiazolones (1989)
    Springer
    Chromatographia 28 (1989), S. 34-38 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Methylisothiazolones ; Preservatives ; Analysis of cosmetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Antimicrobially active formulations based on 2-methyl-3(2H)-isothiazolone and 5-chloro-2-methyl-3(2H)-isothiazolone (Kathon CG, Euxyl K 100) are incorporated into manufactured cosmetics as preservatives. In this paper we report on the analysis of these active components by means of liquid chromatography. It is conventional for the original methylisothiazolone components in cosmetics to be analyzed by reversed phase high-performance liquid chromatography after column chromatographic separation and flash chromatographic purification. In our new analytical method the methylisothiazolones are converted into the respective β-thiosubstituted acrylamide derivatives, which are ionic substances, with the help of the nucleophilic reagent hydrogensulfite. An ion pair high-performance liquid chromatographic method has been developed for the separation and quantification of these derivatives.
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    URL: http://dx.doi.org/10.1007/BF02290380
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    Nucleotide and aldehyde analysis by HPLC for determination of radical induced damage (1989)
    Springer
    Chromatographia 28 (1989), S. 65-68 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Oxygen radicals ; Nucleotides ; Aldehydes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The analysis of two metabolite groups, nucleotides and aldehydes, is necessary for assessment of oxygen radical metabolism during hypoxia and reoxygenation. Nucleotides and their derivatives were determined by HPLC using gradient elution with 10 mM NH4H2PO4 buffer containing 2 mM t-butylammoniumphosphate and acetonitrile. Aldehydes occuring after lipid peroxidation were analyzed by derivatisation to dinitrophenylhydrazones followed by TLC and HPLC separation with methanol/water on an ODS column.
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    URL: http://dx.doi.org/10.1007/BF02290385
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    High-performance-liquid chromatographic separation of 1,3,5-trizine herbicides (1989)
    Springer
    Chromatographia 28 (1989), S. 209-211 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Triazine herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A number of 11 triazine herbicides and 7 of their corresponding metabolites were separated in a single HPLC run. The separation was achieved on a reversed-phase column using gradient elution with acetonitrile/buffer. Detection was by UV absorption at a wave-length of 220 nm.
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    URL: http://dx.doi.org/10.1007/BF02319649
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    Trace enrichment and HPLC analysis of polycyclic aromatic hydrocarbons in environmental samples, using solid phase extraction in connection with UV/VIS diode-array and fluorescence detection (1989)
    Springer
    Chromatographia 28 (1989), S. 203-208 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Polycyclic aromatic hydrocarbons ; Diode array and fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Both the separation of polycyclic aromatic hydrocarbons (PAH's) on tailor made HPLC phases, and their chromatographic enrichment and quantitative determination are of great interest. Because of the generally low concentrations of PAH's in the environment, and the low limiting values in German legislation for drinking water, methods for selective enrichment and sensitive detection are indispensable. On account of their relatively high amounts in soil, the determination of PAH's is valuable for the assessment of the potential danger to ground water by waste materials. These requirements can be fulfilled by used of solid phase extraction on enrichment columns, and fluorescence or UV/VIS diode array detection. For the detection of PAH's in the picogram range, the wavelengths for excitation and emission were time programmed over the chromatogram. With this feature, it is possible to detect all the individual compounds at the highest sensitivity, over the entire analysis.
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    URL: http://dx.doi.org/10.1007/BF02319648
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    A simple highly reproducible gradient system for micro column HPLC (1989)
    Springer
    Chromatographia 28 (1989), S. 289-292 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micro-bore and capillary columns ; Gradient techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A gradient delivery system for microbore and open tubular liquid chromatography is described. A gradient mixing vessel of 5–100μl, or 25–1000μl allows the generation of binary gradients with high reproducibility. The suitability of the system for short packed micro bore columns and open tubular columns is demonstrated.
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    URL: http://dx.doi.org/10.1007/BF02260777
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    A high-performance liquid chromatographic method for determination of flecainide in human plasma using fluorescence detection (1989)
    Springer
    Chromatographia 28 (1989), S. 303-306 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flecainide in plasma ; Fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high performance liquid chromatographic method for the determination of flecainide in serum has been developed. The analysis is performed on a microparticulate silica column. The eluate is monitored by fluorescence detection at an excitation wavelength of 300nm and an emission wavelength of 370nm. No sources of interference were identified and a coefficient of variation of less than 8% was observed on repeated flecainide determinations. The method has a good reproducibility, specificity and accuracy, and can be applied in therapeutic drug monitoring of flecainide in patients.
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    URL: http://dx.doi.org/10.1007/BF02260780
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    Assay for methylnaltrexone in rat brain regions and serum by high-performance liquid chromatography with coulometric electrochemical detection (1989)
    Springer
    Chromatographia 28 (1989), S. 359-363 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Coulometric electrochemical detection ; Methylnaltrexone ; Rat brain and serum analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and sensitive method is described for the determination of methylaltrexone, a quaternary narcotic antagonist, in discrete rat brain regions and serum. Separation and quantitation are performed by reversedphase high-performance liquid chromatography with coulometric electrochemical detection. Perchloric acid extracts of the brain tissue or serum were passed through a normal-phase solid-phase extraction CN column, and methylnaltreexone was subsequently eluted with a mixture of absolute ethanol and 25mM trifluoroacetic acid. Methylnaltrexone gave a linear response over the range of 12.5–100ng in 1.0ml for cerebellar homogenates and 25–200ng in 50μl for serum. The average betweenassay coefficients of variation for methylnaltrexone from 1.0ml of cerebellar homogenate and 50μl of serum were 5.2 and 3.6%, respectively, over the concentration range studied. The within-assay coefficients of variation at 12.5ng/ml cerebellar homogenate and 25ng/50μl for serum were 7.4 and 4.6%, respectively. Analytical recovery of methylanyltrexone, added to cerebellar homogenate and serum samples, were 85 and 89%, respectively. The method was applied to the analysis of methylnaltrexone in discrete rat brain regions and serum after intraperitoneal injection.
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    URL: http://dx.doi.org/10.1007/BF02261014
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    Preparative scale reversed-phase HPLC method for simultaneous separation of carotenoids and carotenoid esters (1989)
    Springer
    Chromatographia 28 (1989), S. 129-132 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carotenoids ; Paprika, Rose hips, Marigold
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the preparative HPLC of carotenoids and carotenoid esters using a self-packing axially-compressed column. The reversed-phase system used employs an RP-18 stationary phase and a mobile phase consisting of a mixture of petroleum spirit, acetonitrile, methanol and tetrahydrofuran. The method is demonstrated for paprika fruit, rose hips and marigold flowers.
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    URL: http://dx.doi.org/10.1007/BF02319633
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    The effect of an organic eluent modifier and pH on the separation of wheat-storage proteins: Application to the purification of γ-gliadins ofTriticum monococcum L (1989)
    Springer
    Chromatographia 28 (1989), S. 133-138 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Wheat proteins ; γ-gliadins ; Effect of pH on separation ; Effect of organic modifier on separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase, high-pressure liquid chromatography has been used to separate similar protein (γ-gliadin) components from 70% ethanol extracts of endosperm flour from two different accessions of the diploid wheatTriticum monococcum L. The effect of acetonitrile as the organic eluent was compared to acetonitrile: 2-propanol (3:1) at two different pH's. Conditions for maximum resolution of the γ-gliadin components were found to be at pH 7.2 with acetonitrile: 2-propanol (3:1) as the eluent. These conditions allowed the components to be obtained in sufficient purity for further charaterization.
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    URL: http://dx.doi.org/10.1007/BF02319634
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    Direct preparative resolution of racemic amino-acids using ligand exchange chromatography (chirallec) (1989)
    Springer
    Chromatographia 28 (1989), S. 337-340 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand-exchange ; Preparative racemate resolution ; Amino-acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Preparative resolutions of racemic amino-acids by ligand-exchange chromatography are described. Base-line resolution of multigram quantities of many racemic solutes was obtained using very simple equipment (open tubular column).
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    URL: http://dx.doi.org/10.1007/BF02261011
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    Physico-chemical modelling of solute retention in reversed-phase HPLC with temary mobile phases (1989)
    Springer
    Chromatographia 28 (1989), S. 354-358 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ternary mobile phases ; Solute retention model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In our previous publications we have established a new physico-chemically grounded retention model valid for the adsorption and partition mechanism of retention using multicomponent mobile phases. Moreover, we have demonstrated its practical usefulness for predicting solute retention in several different chromatographic modes (i.e. in TLC, normal-phase and reversed-phase HPLC) employing binary mobile phases. In this paper we give an ultimate check to the physicochemical correctness of our new retention model, using it for the description of solute retention in reversedphase HPLC systems with ternary mobile phases of the B+AB1+AB2 type. The complexity of these mobile phases and of the possible intermolecular interactions among the consitituent solvents was supposed to rigidly scrutinize the premises of the assumed new approach. We have observed a good agreement between the experimental retention parameter for a number of solutes chromatographed with the use of two different mobile phases of the B+AB1+AB2 type, and the retention parameter calculated according to the assumed model. Therefore, we believe to have sufficiently tested our new approach and confirmed its physico-chemical correctness.
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    URL: http://dx.doi.org/10.1007/BF02261013
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    Optical resolution HPLC column packings carrying penicillin sulfoxide nucleus. Part IV. Effect of substituents in the benzyl ester group on the optical resolution efficiency (1989)
    Springer
    Chromatographia 28 (1989), S. 513-515 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Optical resolution ; Polymeric adsorbents ; Penicillin sulfoxide ; Substituent effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Fourteen new vinyl polymers carrying penicillin sulfoxide nucleus, poly (substituted-benzyl 1-oxo-6-metha-crylaminopenicillanate)s, were synthesized in order to investigate the influence of the substituents on the optical resolution capabilities. The resolution efficiency of the high-performance liquid chromatography columns comprising the obtained polymers were examined usingtrans-stilbene oxide and N-acetyl-1-phenethyl-amine. It was found that some columns resolved both racemates, some one, while the others did not separate either. A polymer which has 2,6-dichlorobenzyl moiety was found to resolve both racemates more effectively than the unsubstituted polymer.
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    URL: http://dx.doi.org/10.1007/BF02261073
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    HPLC determination of the phenolic metabolites of phenoxy alkanoic acid herbicides (1989)
    Springer
    Chromatographia 28 (1989), S. 465-468 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chlorinated phenols ; 4-Aminoantipyrine derivatives of phenols ; Metabolites of phenoxy alkanoic acid herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High performance liquid chromatography (HPLC) has been applied to the separation and determination of o-chlorophenol, 2,4-dichlorophenol, 3,4-dichlorophenol, 2,5-dichlorophenol, and 2,4,5-trichlorophenol in water samples after prior derivatization with 4-aminoantipyrine. These substances are the phenolic decomposition products of the phenoxy-alkanoic acid herbicides: 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4-dichlorophenoxybutyric acid (2,4-DB), and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T). An RP-C18 column was used, with gradient elution starting at 50/50 and changing to 70/30 methanol/water (v/v) after 24 min. Detection was carried out at 470 nm where the 4-aminoantipyrilquinonimine derivatives show maximum absorbance. The method was linear over a concentration range of 5–10,000 ppb phenol in the original water sample. By using an enrichment step a detection limit of 2 ppb phenol could be approached. The method was used to study the degree of degradation of the phenoxy acids to phenols under different conditions of temperature, pH, and UV irradiation.
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    URL: http://dx.doi.org/10.1007/BF02261061
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    Optical resolution of 2-hydroxy acids by high-performance ligand exchange chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 481-486 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand exchange ; Chiral phase ; Optical resolution of 2-hydroxy acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Using an MCl GEL CRS10W column, which was packed with octadecyl silica (ODS) coated with N,N-dioctyl-L-alanine, optical resolution of 2-hydroxy acids was performed. The optical resolution of mandelic acid derivatives and C2 to C5 2-hydroxy acids was carried without any pretreatment. The MCl GEL CRS10W column could resolve amino acids and 2-hydroxy acids. For their selective detection, a post-column method was employed in which the specific color reaction of 2-hydroxy acids with iron(III) ion was utilized. For the analysis of foodstuffs, in which amino acids and 2-hydroxy acids often coexist, the present method was found to be effective in distinguishing between these enantiomers.
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    URL: http://dx.doi.org/10.1007/BF02261065
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    Isolation and quantitative analysis of hydroxylysine glycosides (1989)
    Springer
    Chromatographia 28 (1989), S. 497-501 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Collagen metabolites ; Amino acid derivatives ; Glycosides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Methods are described for the isolation of galactosyl hydroxylysine and glucosylgalactosyl hydroxylysine from collagen and for the quantitative analysis of these hydroxylysine glycosides. The isolation procedure, based upon gel filtration and preparative ionpaired reversed-phase high-performance liquid chromatography, is simple and rapid in comparison with existing methods, allowing the production of tens of milligrams of each glycoside in a single day. Quantitative analysis of the hydroxylysine glycosides is effected by reversed-phase high-performance liquid chromatography with precolumn derivatization (usingo-phthal-dialdehyde) and fluorescence detection.
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    URL: http://dx.doi.org/10.1007/BF02261068
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    Optical resolution HPLC column packings carrying penicillin sulfoxide nucleus. Part III. Radical copolymers and their optical resolution efficiency (1989)
    Springer
    Chromatographia 28 (1989), S. 511-512 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Optical resolution ; Polymeric adsorbents ; Penicillin sulfoxide ; Copolymerization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A methacrylamide carrying penicillin sulfoxide skeleton, benzyl 1-oxo-6-methacrylaminopenicillanate, was copolymerized with methyl methacrylate. The optical resolution efficiency of the columns comprising the obtained copolymers was investigated using a high-performance liquid chromatography system. A copolymer incorporated by 27mol% of methyl methacrylate showed higher chirality recognition capability than the homopolymer, which suggests that the introduction of methyl methacrylate contributes to enriching desired penicillin sulfoxide alignment (i. e., tracticity) along the polymer main chain. An estimated penicillin monomer's number-average sequence length in the copolymer was 2.7.
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    URL: http://dx.doi.org/10.1007/BF02261072
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    Separation of metal acetylacetonates by reversed-phase high-performance liquid chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 519-522 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase chromatography ; Separation of metal acetylacetonates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Using reversed-phase high-performance liquid chromatography acetylacetonate complexes with trivalent metals such as Al(III), Co(III), Cr(III) and Fe(III) have been examined in columns containing RP-2, RP-8 and RP-18 bonded phases. The mobile phase consisted of acetonitrile/water or methanol/water mixtures with various compositions. As shown the order of elution of the acetylacetonates depends on the type of the column packing and on the nature and concentration of the organic modifier in the mobile phase.
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    Chromatographic analysis of penstemide and serrulatoloside by high-performance liquid chromatography and gradient thin-layer chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 24-26 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Penstemide and serrulatoloside
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Penstemide and serrulatoloside, two iridoids of similar molecular structure, were separated by stepwise gradient TLC in a straight-phase systems (silica-ethyl acetate+isopropanol) and by HPLC in a reversed-phase system (ODS-silica — water+methanol).
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    URL: http://dx.doi.org/10.1007/BF02290399
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    Preparative medium pressure liquid chromatographic (MPLC) and semipreparative HPLC separation of furocoumarin isomers (1989)
    Springer
    Chromatographia 27 (1989), S. 591-595 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Overpressured layer chromatography ; Furocoumarin isomers ; Preparative separation of plant extracts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Preparative medium pressure liquid chromatography and semi-preparative high performance liquid chromatography on silica were employed for the isolation of eight furocoumarin isomers (iso-bergapten, angelicin, psoralen, bergapten, pimpinellin, sphondin, xanthotoxin and isopimpinellin). The conditions were transposed from analytical on-line overpressured layer chromatography and analytical high performance liquid chromatography, respectively. The retention data of the analytical on-line overpressured layer chromatographic separation and the preparative medium pressure liquid chromatographic isolation show a linear relationship. Using 15 μm TLC silica 60 as stationary phase a dry-packing procedure aas developed for labomatic medium pressure liquid chromatographic glass columns. The efficiency of the preparative separation techniques was demonstrated by the isolation of the investigated furocoumarins from Heraclei mantegazziani radix and from Pimpinellae radix (Balkan quality).
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    Separation of bromo- and iodosubstituted thyronines by high-performance liquid chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 101-104 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bromo/iodosubstituted thyronines ; Mobile phase optimization ; Radioimmunoassay detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase high performance liquid chromatographic method on C-18 bonded silica is described for the separation of trisubstituted iodo/bromothyronines, which exert thyroid hormone activity. The composition of the mobile phase has been systematically optimized resulting in a ternary mixture of methanol/acetonitrile/water acidified with trifluoroacetic acid. The applicability of ultraviolet absorption detection, amperometric detection and off-line radioimmunoassay was investigated. The latter method allows detection of the different iodo/bromothyronines down to 40–120 ng/l mobile phase; this sensitivity is high enough for application to thyroid hydrolysates in order to clarify the question as to whether bromine can substitute iodine in the biosynthesis of thyroid hormones.
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    Retention of 1,ω-bis-(dialkylamino)-polysulphides and related compounds in reversed-phase HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 113-117 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention contribution of nitrogen ; Effect on methylene and sulphur chains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reaction of secondary amines R2NH with disulfur dichloride S2Cl2 in dichloro methane yields mixtures of bis-dialkylamino polysulphides R2N−Sn−NR2 with sulphur chain lengths varying from ns=2 to 14. The S chains are believed to be non-branched. The compounds form homologous series in each of which sulphur atoms give a constant contribution to retention. The sulphur retention index depends slightly on the carbon number in the terminal alkyl groups R. The presence of nitrogen lowers retention. The index increment of N is ca. −160 units, which is distinctly less negative than values found in alkylamines.
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    LC-MS of enzymatic peptic haemoglobin hydrolysate produced at the pilot-plant level (1989)
    Springer
    Chromatographia 27 (1989), S. 128-134 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion chromatography ; Fast atom bombardment-MS ; Peptic haemoglobin hydrolysate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the ready identification of any peptide isolated from a complex peptic haemoglobin hydrolysate produced on the pilot-plant scale. A combination of size exclusion and reversed-phase, high-performance liquid chromatography have proved to be a useful strategy for fractionation of such a mixture. This technique enabled pure peptides from the total hydrolysate to be obtained. Amino acid analysis and fast atom bombardment mass spectrometry provided the accurate composition and molecular weight of any isolated peptide. Molecular weights are compared with those deduced from size-exclusion chromatography (SEC) and the usefulness of SEC is discussed. The procedure described in this study will be useful for acquiring a better knowledge of such an hydrolysate and could be extended to other crude protein digests.
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    HPLC determination of catabolic amines in silage using their dansyl derivatives and an electrochemical detector (1989)
    Springer
    Chromatographia 27 (1989), S. 216-220 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detector ; Amines ; Silages ; Feedstuffs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of the electrochemical detector (EC) in the high performance liquid chromatography (HPLC) of dansyl derivatives of biogenic amines is reported. Isocratic and gradient elution patterns of synthetic mixtures of putrescine, cadaverine, 1,6-diaminohexane, tryptamine, histamine, tyramine, spermine and spermidine on a reversed phase column are shown. Hydrodynamic voltammograms of standard compounds are presented. The detection limits of the EC are compared with those of ultraviolet and spectrofluorimetric detectors. A chromatographic profile of amines from the proteolytic catabolism of maize silage byClostridia is shown.
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    Retention behaviour of selected flavonoid compounds in NP-HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 625-627 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Normal phase elution ; Silica and cyano columns ; Flavonoid compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary HPLC retention data for a number of flavonoid compounds have been evaluated on normal phase silica and cyano colums according to the Soczewinski-Snyder (S.-S.) model. On the silica phase most of the flavones examined exhibited asymetrical peak shapes indicating strong and mixed retention mechanisms; on the cyano phase the intercept of the S.-S. relationship was independent of any hydroxy substitution pattern or of molecular planarity. A similar behaviour, but with different intercept values, was observed with coumarin and quinone compounds.
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    Rapid reversed-phase chromatographic separation and determination of selenum and tellurium (1989)
    Springer
    Chromatographia 27 (1989), S. 292-296 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Selenium(IV)-tellurium(IV) separation ; Flow-through coulometric detector
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of selenium and tellurium has been investigated with two different reversed-phase chromatographic methods, using P-350 (methyl-bi-isooctyl phosphate) and TBP (tributyl phosphate) as the stationary phases. HCl, HBr, NaCl and NaBr were employed as mobile phase components in both methods. The results suggested that the separation mechanism corresponds to the formation of TeCl (or TeBr) and P-350H (or TBPH) ion associate. A coulometric flow-through detector was applied to determine Se(IV) and Te(IV). Complete separation and quantitative determination of Se and Te could be achieved in 10 minutes.
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    URL: http://dx.doi.org/10.1007/BF02321271
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    Preparative HPLC of carotenoids (1989)
    Springer
    Chromatographia 27 (1989), S. 325-327 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Carotenoid ; Xanthophyll ; Broccoli ; Paprika
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the preparative HPLC of up to 50mg of carotenoid using a self-packing axially-compressed column. Oxygenated carotenoids, xanthophylls, are separated with silica as the stationary phase and acetone/petroleum ether as the mobile phase, while carotenes are separated using magnesium oxide/polyamide as the stationary phase and undiluted petroleum ether as the mobile phase.
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    Applications of HPLC with evaporative light scattering detection in fat and carbohydrate chemistry (1989)
    Springer
    Chromatographia 27 (1989), S. 340-342 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Evaporative light scattering detection ; α, ω-Dicarboxylic and hydroxycarboxylic acids ; Alkylglucosides and glycerides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The advantages of an evaporative light scattering detector in HPLC are demonstrated using the separation of α, ω-dicarboxylic and hydroxycarboxylic acids, alkyl glucosides and mono-, di- and triglycerides as examples. By using this detector reversed phase as well as normal phase gradient HPLC becomes possible for substances with no UV absorption.
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    URL: http://dx.doi.org/10.1007/BF02321281
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    Selectivity of alkyl-bonded phases in reversed-phase liquid chromatography of hydrophobic compounds (1989)
    Springer
    Chromatographia 27 (1989), S. 371-377 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alkyl-bonded silica gel ; Enthalpy ; Van der Waals volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Starting from silica gel with a purity of 99.999%, octadecyl-(ODS), octyl-(C8) and propyl-(C3) bonded silica gels were synthesized, and end-capped by trimethyl groups. The pore size was 150 Å and the specific surface area was 320 m2/g. The ODS and C8 silica gels were stable in both acidic and basic solutions. The selectivity of these bonded-silica gels was examined from the difference of the retention behavior of alkanes (Al−Al), alkylbenzenes (Ph−Al), alkylalcohols (Al−OH) and polyaromatic hydrocarbons (PAH) in aqueous acetonitrile. On these packings the log k′ values decreased in the order Al−Al〉Ph−Al〉PAH〉Al−OH. Furthermore, the chromatographic behavior of these compounds was measured on polymer-coated octadecyl-bonded silica gel (CAP) and octadecyl-bonded vinyl alcohol copolymer gel (ODP). The selectivity was verified from the value of R* of these compounds: $$R = R_v + R^* $$ where R is the retention time, and Rv is the retention time of an alkane having the same Van der Waals volume as the analyte. The R* values indicated that this ODS had more selectivity than C8 and C3, however R* on C8 showed a very good correlation with R* on C3. Their retention behavior on CAP was similar to that of ODS, however, their capacity ratios measured on CAP were smaller than those on ODS. The ODP has selectivity for the retention of aromatic compounds, because PAHs were retained strongly on this column.
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    URL: http://dx.doi.org/10.1007/BF02321286
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    Determination ofAlternaria mycotoxins in foodstuffs by gradient elution liquid chromatography with electrochemical detection (1989)
    Springer
    Chromatographia 27 (1989), S. 425-430 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Alternaria mycotoxins ; Food analysis ; Electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The electroactivity of majorAlternaria mycotoxins has been explored in order to devise a liquid chromatographic-electrochemical detection (LC-EC) method for the determination of these toxic metabolites in fungal cultures and in naturally contaminated foodstuffs. Alternariol, alternariol methyl ether, altertoxin-I and altertoxin-II have been found to be electroactive and could be detected at sub-nanogram levels. Advantages and limitations of dual electrode (screen mode) coulometric detection and single electrode amperometric detection are presented and discussed. The feasibility of electrochemical detection in gradient elution liquid chromatography as well as its applicability to the analysis of contaminated foodstuffs is demonstrated.
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    URL: http://dx.doi.org/10.1007/BF02319558
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    Automatic measurement of some common herbicides by LC using simultaneous UV detection and electrochemical detection in series (1989)
    Springer
    Chromatographia 27 (1989), S. 431-435 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; UV diode array detection ; Electro chemical detection ; Herbicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An automated procedure is described for simultaneous UV detection at three different wavelengths and electro chemical detection in series of some residual herbicides. UV spectra of nine compounds of different compound groups are presented. Liquid-liquid extraction with dichloromethane and an enrichment of about one thousandfold has been used. Recovery rates after enrichment and detection limits of four s-triazine, three phenyl urea herbicides, metazachlore and metamitrone in river and drinking water are shown. It is concluded that the herbicides examined can be detected at levels between 10ng l−1 and 50ngl−1, without the necessity of derivatisation or clean-up processes.
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    URL: http://dx.doi.org/10.1007/BF02319559
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    Size exclusion chromatography on porous fractals (1989)
    Springer
    Chromatographia 27 (1989), S. 257-263 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size exclusion ; Fractal dimension ; Retention model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Some porous packings used in chromatography have been claimed to be fractals with a scale of sizes a〈l〈L, where a is a molecular size and L is the size of the largest pores. For a fractal porous packing, the excluded volume for molecules in solution in the vicinity of the packing surface is directly related to Df, the fractal dimension of the pore surface (2〈Df〈3). Since retention in size exclusion chromatography is itself directly related to this excluded volume, the fractal nature of the packing provides a model of retention in this technique. According to this model there is a linear relationship between log Rs and log(1-Kd), where Rs is the hydrodynamic radius of the solute macromolecules and Kd the distribution coefficient. The fractal dimension is derived from the slope of this plot. Size exclusion chromatographic retention data have been analyzed according to the model. It is found that some HPLC packings are fractals with fractal dimensions ranging from about 2.15 to 2.6, depending on the material. Such a large range of Df values indicates large variations in the selectivities and domains of applications of the different packings. For some classical gel filtration chromatographic gels, the fractal retention model does not seem to apply.
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    Simultaneous flow rate and temperature programming based on computer-assisted retention prediction for the separation of PTH-amino acids in reversed-phase microcolumn liquid chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 417-424 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Micro-columns ; Flow rate and temperature programming ; PTH amino acid derivatives
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of phenylthiohydantoin (PTH) amino acid derivatives by flow rate and temperature programming in reversed-phase micro-column liquid chromatography (LC) has been investigated. For both programming modes a microcomputer-assisted retention prediction system (REPRES) was constructed. The performance of this system has been evaluated by comparing actually measured retention data to those predicted. Excellent agreements between those data were found. It is clearly indicated that simultaneous flow rate and temperature programming can improve the separation of PTH-amino acids in reduced analysis time.
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    HPLC and electrophoresis — Competitors or partners (1989)
    Springer
    Chromatographia 28 (1989), S. 89-91 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrophoresis ; Comparison of HPLC and electrophoresis ; Proteins, peptides and amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Protein structure analysis is an indispensible tool in modern biological research. However, the isolation of a protein or the separation of peptides in a form suitable for sequence analysis is a considerable technical challenge. The two predominant separation methods in protein biochemistry are chromatography and electrophoresis. In this paper the position, advantaged and disadvantages of both HPLC and electrophoresis for the separation of amino acids, peptides and proteins in protein structure analysis are discussed.
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    URL: http://dx.doi.org/10.1007/BF02290389
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    Evaluation of synthetic procedures for the chemical modification of alumina for HPLC (1989)
    Springer
    Chromatographia 28 (1989), S. 565-568 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; New bonded phases ; Alumina ; Protein separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Several reactions are tested for the chemical modification of alumina. These include the following: chlorination of the surface hydroxyls followed by reaction with an organolithium compound; chlorination of the surface hydroxyls followed by reaction with a Grignard reagent; chlorination of the surface hydroxyls followed by reaction with an amine; chlorination of the surface hydroxyls followed by reaction with an alcohol; direct reaction of the alumina with an organochloroalane and direct reaction of the alumina with an alcohol. Only the first reaction gave a product which contained enough bonded organic material to be easily detected by FTIR. Preliminary stability tests show that the product of the first reaction retains the bonded organic material when exposed to nonpolar and polar organic solvents as well as aqueous solutions of pH 1.0, 7.0 and 12.0. Chromatographic testing establishes reversed-phase behavior for alkylarylketones as solutes and the bonded phase displays good biocompatibility for a series of protein standards.
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    Separation of adenosine triphosphate and its degradation products in innervated muscle of the frog by reverse phase high-performance liquid chromatography (1989)
    Springer
    Chromatographia 28 (1989), S. 610-612 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Adenosine phosphates ; Adenosine phosphate degradation products ; Innervated frog muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Adenosine mono-, di- and triphosphates, inosine monophosphates, adenosine, inosine and hypoxanthine were separated in a single run by high-performance liquid chromatography with UV detection. AC-18 reversephase column was used. An isocratic elution with 100mM phosphate buffer (KH2PO4) pH6.5 and 1.2% methanol, followed by a 5 minute linear gradient up to 15% methanol after the 10th minute was performed during each run with a flow rate of 1.25ml/min. The time required for each analysis was 25 minutes. The detection limit for each substance ranged from 3 to 5 pmol. All the substances under study were detected in the incubation medium when adenosine triphosphate was exogenously applied to the innervated frog sartorius muscle.
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    Molecular interactions in liquid adsorption chromatography with mixed mobile phase. Solvation of the chromatographed substance in a ternary mobile phase (1989)
    Springer
    Chromatographia 28 (1989), S. 151-156 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Molecular interactions ; Association effects ; Analyte solvation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The linear Jaroniec equation has been utilized for the description of chromatographic systems in which the test substance molecule is solvated by the solvent molecules. A possibility of the formation of multimolecular solvates in the bulk phase has been confirmed. The measurements were made using liquid adsorption chromatography with ternary mobile phase.
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    Immobilized enzymes as chromatographic phases for HPLC: The chromatography of free and derivatized amino acids on immobilized trypsin (1989)
    Springer
    Chromatographia 28 (1989), S. 551-555 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral separations ; Trypsin on silica ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new HPLC stationary phase was synthesized by the covalent immobilization of the enzyme trypsin (TRYP) on silica. The hydrolytic activity of the immobilized enzyme was 72% of the activity of an equivalent molar amount of free TRYP. The initial chromatographic studies indicate that this phase can be used for chiral separations of enantiomeric O- and N,O-derivatized amino acids which are natural substrates on TRYP and that the stereochemical resolutions are a result of the activity of the enzyme.
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    Effect of destruction of chemically bonded reversed phases by hexamethyldisilazane during end-capping (1989)
    Springer
    Chromatographia 28 (1989), S. 574-578 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phases ; End-capping ; Destructive effects on bonded phases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Hexamethyldisilazane (HMDS) and trimethylchlorosilane (TMS) have been used as a secondary deactivation (end-capping) reagents for packing materials for RP HPLC. Three types of chemically bonded phases (CBP) with different structures and different coverage densities were used. The destructive effects of HMDS on the coverage density of chemically bonded C18 and C8 phases is discussed.
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    Retention characteristics of aliphatic compounds on cellulose acetates as a stationary phase with an aqueous mobile phase (1989)
    Springer
    Chromatographia 28 (1989), S. 279-284 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cellulose acetate ; Acetyl content ; Temperature effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Cellulose and cellulose mono-, di-, and triacetate were used as stationary phases for liquid chromatography with water as a mobile phase, and the retention behavior of alcohols, ethers, ketones, and chlorides was examined. For cellulose acetate columns, the logarithm of the specific retention volume, (logV g * ), correlated linearly with the logarithm of partition coefficient between 1-octanol and water (log Ko/w), for each homologous group, but all solutes were unretained on cellulose columns. With the exception of chlorides, the intercept values of the log V g * –log Ko/w regression lines increased significantly with increase of acetyl content of cellulose acetates, but the slopes of the regression lines changed little. This suggests that hydrophobic interaction between the acetyl groups of cellulose acetates and the alkyl chains of the solutes is the dominant factor in the retention. The capacity factors for 1-alcohols with cellulos diacetate column indicated a maximum at a column temperature of about 40°C. This unique retention behavior was assumed to be caused by small structural change of the cellulose acetate polymer, because this temperature effect on the retention corresponded with effects observed by differential scanning calorimetry (DSC).
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    Chromatographic investigations of furocoumarins fromHeracleum genus fruits (1989)
    Springer
    Chromatographia 28 (1989), S. 161-166 
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    ISSN: 1612-1112
    Keywords: Thin-layer chromatography ; Column liquid chromatography ; Micropreparative separations ; Furocoumarins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Furocoumarins from extracts ofHeracleum genus fruits were separated using normal and reversed phase TLC and HPLC and isolated in the milligram scale using overloaded systems of column chromatography. Binary or ternary solvents containing a polar modifier (methanol, diisopropyl ether or acetonitrile) were used as the mobile phases.
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    Influence of mobile phase composition on the adsorption of hen egg-white proteins to anion-exchange cellulose (1989)
    Springer
    Chromatographia 28 (1989), S. 170-178 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange ; Mobile phase optimisation ; Egg-white proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Factors influencing the capacity of Whatman QA52 anion-exchange cellulose for hen egg-white proteins have been investigated. While simply increasing the concentration of protein in the feedstock increases the loading there is a concomitant reduction in binding efficiency in a single pass through the column. Substitution of buffer by water in the mobile phase during sample preparation, thereby reducing the ionic strength of the feedstock, had the effect of significantly increasing protein capacity whilst improving binding efficiency. During column loading large changes in pH of the mobile phase were observed although this had no apparent effect on the chromatography for this system.
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    URL: http://dx.doi.org/10.1007/BF02319642
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    Design of enzyme reactors as chromatographic columns for racemic resolution of amino acid esters (1989)
    Springer
    Chromatographia 28 (1989), S. 193-196 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Immobilized enzymes ; Racemic resolution of amino acid esters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Racemic resolution of aromatic and aliphatic amino acid esters into L-amino acid and D-amino acid ester via LC and HPLC is achieved by using enzyme reactors as chromatographic columns. For this purpose α-chymotrypsin and trypsin are immobilized on Eupergit C, Sepharose 4B and Lichrosorb-Diol.
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    A chromatographic method for hydrophobicity investigations of sorbents (1989)
    Springer
    Chromatographia 28 (1989), S. 258-262 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded stationary phases ; Evaluation of the hydrophobicity of sorbents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The energy of interaction (∈0) between the methylene group and the surface of a sorbent is proposed for use in the quantitative evaluation of the hydrophobicity of a sorbent. A method was developed to determine the ∈0 parameter from chromatographic measurements using the investigated sorbent as the stationary phase and linear methylene-containing homologous series, e.g., alkanols, amino-alkanes, etc., as the test compounds. The effectiveness of this method is demonstrated by using, as examples, a series of bonded stationary phases and a series of cross-linked copolymeric sorbents differing in the concentration of the hydrophobic groups. The proposed method is compared with the Martin rule used extensively in the chromatography of oligomers.
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    Computer-assisted transposition of conditions in high-performance thin-layer chromatography to high-performance liquid chromatography for the separation of pesticides (1989)
    Springer
    Chromatographia 28 (1989), S. 285-288 
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    ISSN: 1612-1112
    Keywords: Thin-layer chromatography ; Column liquid chromatography ; Mobile phase optimization ; HPTLC transposition to HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A computer-assisted method is presented for mobile phase selection for the optimal separation of pesticides by HPTLC and HPLC. The system is based on a plot of solute retention value and separation criterion vs. binary mobile phase composition for graphic optimization. The result of HPTLC can be transposed to HPLC for optimal separation. The transposition equation is given.
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    HPLC determination of the flavonoid glycosides fromBetulae folium extracts (1989)
    Springer
    Chromatographia 28 (1989), S. 311-312 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flavonoid glycosides ; Betula
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The main flavonoid glycosides ofBetulae folium extracts (quercetin-3-glucuronide, myricetin-3-galactoside, hyperosid, quercetin-3-arabinoside and quercetin-3-rhamnoside) have been separated by isocratic elution on a C18 Aquapore RP-300 column. Elution was performed with 17% isopropanol at pH 6.2 confirming the validity of this eluent for the analysis of the flavonoid glycosides.
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    High-performance liquid chromatographic resolution of enantiomers on chiral epoxy polymer-coated silica gel (1989)
    Springer
    Chromatographia 28 (1989), S. 477-480 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phase ; Resolution of amino acid derivatives ; Enantioseparation by HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A chiral stationary phase for the separation of some D-and L-amino acid derivatives using a new resolving agent is described. The enantiomeric resolution was accomplished by normal phase high-performance liquid chromatography. The support was easily prepared by coating an epoxy polymer of L-valinamide on aminopropylsilanized macroporous silica. The influence of subambient temperatures on the enantioselectivity was also examined.
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    The effect of alcoholic mobile phase modifiers on retention and stereoselectivity on a commercially available cellulose-based HPLC chiral stationary phase: An unexpected reversal in enantiometric elution order (1989)
    Springer
    Chromatographia 27 (1989), S. 15-18 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral recognition process ; Enantiomeric elution order ; Mobile phase modifiers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three enantiomeric solutes, a sulphoxide, a piperidine derivative and a methyl ester have been chromatographed on an HPLC chiral stationary phase (CSP) based upon cellulose-tribenzoate (Chiralcel OB-CSP). The mobile phases used in the study were composed of hexane modified with homologous series of primary, secondary and cyclic alcohols. Interesting reversals in enantiomeric elution order have been observed for 2-phenoxypropanoic acid methyl ester associated with changes in chain length or ring size of the alcohol mobile phase modifier. The results of the study suggest that at least two chiral recognition mechanisms operate on the OB-CSP and point out the importance of acquiring elution order data in all studies involving chiral stationary phases.
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    Prediction of HPLC retention times in gradient elution from isocratic data application to a set of non-homologous compounds and different stationary phases (1989)
    Springer
    Chromatographia 27 (1989), S. 19-23 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Prediction of retention times ; Gradient elution ; Substituted quinolines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A chromatographic model able to predict, from experimental isocratic data, retention times of solutes under gradient conditions has been proposed previously. The prediction was shown to be totally independent of the chemical properties of both solutes and eluents. In order to further check the general validity of the theory, the model has now been applied to a nonhomologous set of compounds, namely a range of substituted quinolines (methyl-, hydroxy- and amino-) and several different stationary phases. Results show a dependence on the stationary phase and, to a lesser extent, on the chemical structure of the solutes. The possible sources of errors are discussed. The generality of the method holds, within acceptable limits, if predictions concern the same type of stationary phase.
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    Analysis of thiols by HPLC after fluorescent prelabelling with 4-(6-methylnaphthalen-2-yl)-4-oxobuten-2-oic acid (1989)
    Springer
    Chromatographia 27 (1989), S. 185-190 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiol analysis ; Fluorimetric detection ; Derivatization with 4-(6-methylnaphthalen-2-yl)-4-oxobuten-2-oic acid
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of 4-(6-methylnaphthalen-2-yl)-4-oxobuten-2-oic acid as a fluorogenic reagent in pre-column derivatization for the high-performance liquid chromatography (HPLC) of biologically important thiols (L-cysteine, glutathione, N-acetylcysteine, homocysteine and mercaptopropionylglycine) was investigated. The aroylacrylic acid reacts selectively and rapidly (15 min. at room temperature) with the thiol compounds to give stable fluorescent adducts which can be separated by reversedphase HPLC and detected fluorometrically (λex 300nm); λem 445nm). The experimental conditions for the thiol derivatization and chromatographic separation are discussed. Applications to the determination of N-acetylcysteine, mercaptopropionylglycine and cysteine are described.
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    URL: http://dx.doi.org/10.1007/BF02260443
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  • 91
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    Chromatographic and potentiometric determination of dissociation constants of weakly basic Aroma compounds (1989)
    Springer
    Chromatographia 27 (1989), S. 194-200 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dissociation constants ; Potentiometric titration ; 2,4-Dimethylthiazole ; Trimethylpyrazine ; Methyl anthranilate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase liquid chromatography on two stationary phases—octadecylbonded silica Partisil ODS-3 and polystyrene-divinylbenzene resin PRP-1—and potentiometric titration in the water/methanol mobile phase were investigated in order to determine the dissociation constants of three weakly basic aroma compounds, namely trimethyl pyrazine, 2,4-dimethyl thiazole and methyl anthranilate. The data obtained from both methods are quite consistent and compare favourably to values found in the literature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260445
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  • 92
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    High-performance liquid chromatographic determination of (−)-cathinone in plasma (1989)
    Springer
    Chromatographia 27 (1989), S. 201-204 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cathinone metabolites ; Plasma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography (HPLC) for the determination of (−)-cathinone in rabbit and human plasma has been studied. The problem of dimerization during extraction from plasma was satisfactorily resolved. Detection was by UV at 257 nm. Concentration levels as low as 24 ng ml−1 were satisfactorily determined. This level of sensitivity should be adequate for the detection of (−)-cathinone in the blood of khat users and also for the quantitative determination of (−)-cathinone in blood for pharmacokinetic purposes. The applicability of the assay procedure to pharmacokinetic studies is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260446
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  • 93
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    A HPLC method for specific determination ofα-amylase and glucoamylase in complex enzymatic preparations (1989)
    Springer
    Chromatographia 27 (1989), S. 328-332 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Glucose, maltose and maltotriose ; α-Amylase and glucoamylase ; Microfungal cultures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In the hydrolysis of soluble starch by mixtures of α-amylase and glucoamylase, the ratios maltose/glucose and maltoriose/glucose linearly depend, over a wide range, on the relation between both enzymes and are independent on the activity level of the enzymatic preparation. HPLC determination of hydrolysis products (glucose, maltose and maltotriose) of soluble starch by mixtures of these enzymes, after incubation under controlled conditions, is a rapid method for the evaluation of the relative levels of each enzyme in the mixtures. The method, first developed using pure commercial amylases, is applied, with consistent results, to cell free media ofAspergillus niger cultures on a glycogen-rich effluent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02321279
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  • 94
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    A study of the practical limitations of principal components analysis and the labelling of unresolved HPLC peaks (1989)
    Springer
    Chromatographia 27 (1989), S. 343-358 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Principal components analysis (PCA) ; Iterative target transformation factor analysis (ITTFA) ; Peak labelling ; Chromatographic peak deconvolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The method of iterative target transformation factor analysis (ITTFA) used in conjunction with second derivative peak finding has shown to be a practical method for the peak deconvolution and reconstruction of HPLC chromatograms and spectra. The second derivative method of peak finding is acceptable for resolutions above 0.5 for peaks of similar heights. Above 0.5 resolution the labelling gives correct results where the spectra are substantially different and also when reasonably similar. Below this value the peak labelling was still accurate where the spectra were different. Solvent effects on the spectra of the compounds studied are small and do not hinder the peak labelling process. Thus small “local” libraries are feasible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02321282
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  • 95
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    Separation and determination of nitrite ion by affinity chromatography with cyano(pheophytinato a)cobalt(III) charged column (1989)
    Springer
    Chromatographia 27 (1989), S. 461-464 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chlorophyll-bonded stationary phase ; Cyano(pheophytinato a)cobalt(III) ; Pheophytin a
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation and determination of the nitrite ion by affinity chromatography is described. The good separation of the nitrite ion was obtained by using cyano-(pheophytinato a)cobalt(III) bonded octadecylsilica as the stationary phase and water of pH 4.3 adjusted by acetic acid as the mobile phase. Conventional ion chromatograph was also used for the analysis of the nitrite ion. For the synthetic samples prepared by mixing the nitrite and nitrate ions, analytical values obtained by affinity chromatography were in agreement with calculated values and close to the analytical values obtained by ion chromatography. In the proposed affinity chromatography, the nitrite and nitrate ions could be determined in the concentration range of 0.15–1.0ppm and 0.1–1.0ppm with relative standard deviations (n=10) of 5.3% and 4.7%, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02319564
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  • 96
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    Determination of atmospheric ammonia as m-toluamide by denuder sampling and HPLC-UV detection (1989)
    Springer
    Chromatographia 28 (1989), S. 27-30 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Atmospheric ammonia ; m-Toluamide derivative ; Annular denuder
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple and reliable method for routine measurement of ammonia in ambient air is described. It is based on the collection of ammonia on H3PO3-coated annular denuders and its subsequent derivatization withm-toluoyl chloride (MTC) in alkaline acetonitrile. The resultingm-toluamide is determined by reversed phase HPLC with UV detection at 230 nm. The limit of dotection is about 0.3μg m−3 for NH3 in air samples collected at 151 min−1 for one hour.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290378
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  • 97
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    High-performance-liquid chromatography ofThermus aquaticus 50S and 30S ribosomal proteins (1989)
    Springer
    Chromatographia 28 (1989), S. 39-44 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thermus aquaticus ; Ribosome ; 50S and 30S subunit proteins ; Gel electrophoresis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The ribosomal 50S and 30S subunit proteins (r-proteins) ofThermus aquaticus have, for the first time, been characterized by size exclusion chromatography (SEC) and by reversed phase high performance liquid chromatography (RPC). To ensure that the best resolution in the RPC was obtained. the elution conditions, such as gradient time, flow rate, temperature, ionic strength of the eluent and the type of stationary phase were optimized. Correlation between experimentally found retention times and those predicted by DryLab G was better than 0.7% over 30 peaks. Protein fractions from RPC runs were desalted and processed by gel electrophoresis so that the ribosomal proteins could be identified by their position on SDS-polyacrylamide gels. The enhanced speed and quality of separation which has been achieved in this study is expected to bring advantaces in experimental work with ribosomal proteins as well as with other biopolymers. In our case the high resolution technique provides a basis for the preparation of a collection of individual ribosomal protein components for future rRNA-protein interaction studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290381
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  • 98
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    Simulation of peak profiles in non-linear HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 321-324 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Simulation of peak profiles ; Rouchon model ; LEA model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The possibilities and domain of applicability of the ideal chromatography model for calculating peak profiles in non-linear chromatography are analyzed. For this purpose we used the main conclusion of the model of a layer of equilibrium adsorption (LEA model), which determines the difference between ideal and non-ideal chromatography in terms of the relative length of a chromatographic column. It is shown that the experimental data of non-linear high-performance liquid chromatography can be approximated in terms of the elementary analytical relations known in the theory of ideal chromatography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02321277
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  • 99
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    Direct determination of the racemate ratio of labetalol hydrochloride by HPLC (1989)
    Springer
    Chromatographia 27 (1989), S. 364-366 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Labetalol ; Separation of racemic diastereomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A direct, isocratic, reversed phase HPLC procedure is developed for the separation of the diastereomeric racemates of labetalol, a combined α- and β-adrenoreceptor antagonist. The aminoalcohol-type diastereomers were resolved on a C18 column using methanolwater-25% ammonia 27-75-2 mobile phase and detection at 220nm. The procedure is simple and convenient to carry out. The method may be of use in the determination of the individual diastereomeric racemates of labetalol in different forms such as bulk substance, pharmaceutical dosage preparations and biological fluids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02321284
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  • 100
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    Correlation between retention and the C18 silica surface coverage in reversed-phase liquid chromatography (1989)
    Springer
    Chromatographia 27 (1989), S. 378-384 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phases ; Retention and surface coverage ; Phase ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Members of three homologous series and five non-homologous solutes with various functional groups were chromatographed on a series of well-characterized C18 reversed stationary phases with a range of methanol-water mobile phases. Measured capacity factors of solutes were correlated with the concentration of C18 ligands on the stationary phase. A linear relationship with the slope depending on a solute molecular structure and the volume fraction of methanol in the mobile phase was obtained. A method for the evaluation of phase ratio is also proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02321287
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