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  • Column liquid chromatography  (68)
  • Springer  (68)
  • National Academy of Sciences
  • Periodicals Archive Online (PAO)
  • 1995-1999
  • 1985-1989  (68)
  • 1980-1984
  • 1986  (68)
Collection
Keywords
Publisher
  • Springer  (68)
  • National Academy of Sciences
  • Periodicals Archive Online (PAO)
  • Wiley-Blackwell  (1)
Years
  • 1995-1999
  • 1985-1989  (68)
  • 1980-1984
Year
  • 1
    Electronic Resource
    Electronic Resource
    Determination of urinary 5-S-cysteinyldopamine by high-performance liquid chromatography with electrochemical detection (1986)
    Springer
    Chromatographia 21 (1986), S. 645-647 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrochemical detection ; Cysteinyldopamine ; Tyrosinase ; Autoxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 5-S-Cysteinyldopamine, a new metabolite of dopamine, was determined in urine by high-performance liquid chromatography with electrochemical detection. The catechol was detected in 14 of 21 melanoma patients and 7 of 21 normal subjects; the highest values were 657 μg/day for melanoma patients and 44 μg/day for normal subjects. These results suggest that the cysteine conjugate may arise from autoxidation of dopamine but tyrosinase may also participate in the oxidation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311920
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  • 2
    Electronic Resource
    Electronic Resource
    Optimization of a reaction detector for analysis at the femtomol level of carbamate insecticides by HPLC (1986)
    Springer
    Chromatographia 21 (1986), S. 136-142 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemical reaction detector ; Carbamate insecticides ; Quantitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the determination of trace amounts of carbamate insecticides in vegetables the combination of liquid chromatography with post column chemical derivatization (chemical reaction detector) is used. In a two step reaction detector the carbamates are firstly saponified in 0.01 M sodium hydroxide at 80°C with a reaction time of 30sec. To this mixture OPA reagent is added to detect the methylamine generated in the saponification. Optimization strategies for this reaction are demonstrated. At a temperature of 80 °C a reaction time of 80 sec is sufficient for quantitative transformation of the methylamine. The peak dispersion can be reduced and hence the detection limit improved by decreasing the diameter of the tubes and by diminishing dilution through the addition of reagent. A 1∶24 ratio of reagent to column (reactor) effluent is possible with cyclone-type mixers. The quantitation of carbamates in different vegetables is demonstrated. The detection limit is 20ppb at a signal to noise ratio of 10∶1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311741
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  • 3
    Electronic Resource
    Electronic Resource
    Optimization of enantiomeric separations with chiral bonded phases (1986)
    Springer
    Chromatographia 21 (1986), S. 205-213 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral phases ; Optimization of separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation and properties of chiral bonded phases with amino acid groups are described. These phases were used in non-polar eluents and in aqueous systems in the presence of Cu2+ ions in the ligand-exchange mode. The optimization of chiral resolution is demonstrated for both cases. With non-polar eluents similarity between bonded groups and solutes is required. The elution could be accelerated by non-protonic moderators. Ligand-exchange separation is influenced by the copper content of the eluent and the stationary phase, the organic moderator concentration, the pH and ionic strength of the buffer and by the temperature. Structural requirements of both the bonded groups and of the solutes for chiral separation are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311888
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  • 4
    Electronic Resource
    Electronic Resource
    Linear solvation energy relationships. A comparison of molar volume and intrinsic molecular volume as measures of the cavity term in reversed phase liquid chromatography (1986)
    Springer
    Chromatographia 21 (1986), S. 473-477 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase capacity factors ; Cavity term ; Molar volumes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Reversed-phase liquid chromatographic capacity factors are well correlated by an equation of the form: $$logk' = (logk')_0 + mV/100 + s\pi ^* + b\beta + a\alpha $$ wheremV/100 measures the cavity term and π*, β, and α are the solvatochromic parameters that measure solute dipolarity/polarizability, hydrogen bond acceptor basicity, and hydrogen bond donor acidity respectively. Liquid molar volume (molecular weight divided by liquid density at 20°C) $$\bar V$$ , and computer-calculated intrinsic (van der Waals) molecular volume, $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{V} _I $$ , are compared as measures of the cavity term in a number of correlations. $$\underset{\raise0.3em\hbox{$\smash{\scriptscriptstyle-}$}}{V} _I $$ leads to more precise correlations as well as to a “cleaner” dissection of the multiple solute/solvent interactions. The opposing exoergic effect of solvent donor/solute acceptor hydrogen bonding, and endoergic cavity term are the main factors influencing HPLC capacity factors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02341273
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  • 5
    Electronic Resource
    Electronic Resource
    Determination of pyridate and its main metabolite CL-9673 in plant materials (1986)
    Springer
    Chromatographia 22 (1986), S. 40-42 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pyridate ; CL-9673 ; Reversed phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The application of a simple reversed-phase, HPLC-UV method for the determination of the contact herbicide pyridate and its main metabolite 3-phenyl-4-hydroxy-6-chloropyridazine-known as CL-9673-in green cereals, grains and straw is described. The method is based on a simple extraction, separation of pyridate from its metabolite, hydrolysis of pyridate to CL-9673, high-performance liquid chromatographic separation of CL-9673 in both fractions using only one reversed phase column and UV-detection. The method is sensitive down to 3 ngg−1 CL-9673 in green plants and grain and 5ngg−1 in straw. In the range 0.05–1.0mgkg−1 recoveries are between 73.7% and 109% from green plants, between 77.7% and 102% from grains and between 77.3% and 87.5% from straw.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257294
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  • 6
    Electronic Resource
    Electronic Resource
    Liquid chromatographic capacity factor as an indicator of lipophilicity in a series of betablocker drugs (1986)
    Springer
    Chromatographia 22 (1986), S. 48-50 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Betablocker drugs ; Lipophilicity ; Capacity factors ; Distribution coefficients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The reverse-phase, high-pressure liquid chromatographic capacity factors (k') of a series of 18 betablocking agents were determined in order to establish correlations with their distribution coefficient values (D), obtained from four bibliographic sources. Under the three pH conditions studied (3.5, 6.2 and 7.5) statistically significant linear correlations (p〈 0.002) between log k' and log D values were obtained for the four series studied. In this series it is concluded that the k' factor is a useful and reliable relative lipophilicity parameter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257296
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  • 7
    Electronic Resource
    Electronic Resource
    A limit to alternate column recycle chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 81-87 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Recycle chromatography ; Pressure dependence ; Capacity factor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It was found experimentally that the potential for routine, rapid high-efficiency separations by alternate column, recycle, reversed-phase chromatography is limited by the increase of capacity factors with pressure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257304
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  • 8
    Electronic Resource
    Electronic Resource
    Specific retention behaviour of metal (III) tetraphenylporphyrins in non-aqueous, reversed high-performance liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 43-47 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Metalloporphyrins ; 5,10,15,20-Tetraphenylporphine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The Co(II), Ni(II), Fe(III) and V(IV) complexes of tetraphenylporphine (TPP) can be eluted at short retention times from a LiChrosorb RP-18 column with pure ethanol. However, both Mn(III) and Co(III) complexes of metal TPP chloride type are so strongly retained on the column that they cannot be eluted. While the retention of other metal teraphenylporphine complexes was not affected, that of the metal(III) complexes of the TPP chloride type especially MnTPPCl and CoTPPCl, decreases dramatically with an increase in the concentration of NH4Cl added into the mobile phase; a linear relationship between logk' and log[NH4Cl], with the slope of about−1, has been observed for these two metal(III) complexes in the NH4Cl concentration range from 2.5×10−4 to 1.3×10−2 mol/l. Thus, the specific control of the retention of the metal(III) complexes is enabled by conditioning the NH4Cl content of the mobile phase, and the chromatographic separation is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257295
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  • 9
    Electronic Resource
    Electronic Resource
    Factors affecting adsorption of organic solutes on cellulose acetate in an aqueous solution system (1986)
    Springer
    Chromatographia 22 (1986), S. 55-58 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; 1-Octanol/water partition coefficient ; Cellulose acetate ; Reverse osmosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The adsorption properties of esters, aldehydes, ethers and amides on cellulose acetate, which is commonly used as a reverse osmosis membrane material, in an aqueous solution system were measured by high-performance liquid chromatography. The adsorption property was characterized with the specific retention volume. For a noncyclic homologous series the logarithm of the specific retention volume was linearly correlated with the logarithm of the partition coefficient between 1-octanol and water. The fact that the slopes of these regression lines are almost identical confirms that the dominant effect on adsorption is the hydrophobic interaction between cellulose acetate and the solute molecule. The intercept represents the effect of the polar groups on adsorption. The effect of the polar group decreases as follows: ―C(O)O―, ―CO―, HCON〈 〉 CH3CON〈 〉 ―OH, ―O―.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257298
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  • 10
    Electronic Resource
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    Equilibrium between α- and β-isomers of dihydroartemisinine and its multiple-peaks in high-performance liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 77-80 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Dihydroartemisine ; Interconversion equilibrium ; Multiple-peaks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The interconversion between the α- and β-isomers and the multiple-peaks of dihydroartemisinine (dihydroqinghaosu) were investigated in reversed-phase, highperformance liquid chromatography. A convenient method using the Gaussian distribution function instead of the Schmidt graphical method for the theoretical calculation of the “diffuse” probability curves versus the fraction of the dead time on column as β form was introduced. Based on the theoretical probability curves and the experimental multiple-peak chomatograms, the effects of temperature and flow velocity on the accuracy and precision of analysis of dihydroartemisinine are indicated and the activation energy of the interconversion between α- and β-isomers of dihydroartemisinine is estimated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257303
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  • 11
    Electronic Resource
    Electronic Resource
    Nucleotide pools and energy charges of smooth molluscan muscles analysed by reversed-phase, ion-pair, high-performance liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 99-102 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Nucleotides ; Mytilus edulis ; Smooth muscle
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the analysis of the 5′ mono-, di- and triphosphates of adenosine, guanosine, uridine and cytidine, as well as uridinediphosphate-glucose and cyclic AMP. Separation is achieved by reversed-phase ion-pair chromatography with linear gradient elution. Application of this method to the analysis of nucleotides in smooth molluscan muscles is described, including the determination of cAMP-levels and the calculation of energy charges for all of the four nucleotide systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257308
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  • 12
    Electronic Resource
    Electronic Resource
    High-performance liquid chromatographic separation of hematoporphyrin and its nickel, copper and zinc complexes on octadecyl-bonded stationary phase (1986)
    Springer
    Chromatographia 22 (1986), S. 132-134 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Porphyrin ; Metalloporphyrin ; Hematoporphyrin IX
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The feasibility of reversed-phase high-performance liquid chromatography for the separation of metal complexes of hematoporphyrin IX (Hp) is described. The retention order, Zn-complex〈Hp (free acid)〈 Ni-complex〈Cu-complex, is regular on an octadecylbonded stationary phase with different compositions of an aqueous methanol mobile phase. These four compounds can be successfully separated within about 8 min on a LiChrosorb RP-18 column (250×4-mm i.d.) with a 85:15 (vol/vol) mixture of methanol and phosphate buffer (pH 3) at a flow rate of 1 ml/min.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257313
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  • 13
    Electronic Resource
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    Analysis of flavonol aglycones in wine extracts by high performance liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 157-159 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Flavonol aglycones ; Isocratic elution ; Wine phenolics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC isocratic elution procedure which allows the separation of flavonol aglycones in wine without interference from other phenolics of low molecular weight is described. The method has been applied to the separation, identification and quantitative estimation of flavonol aglycones in ether extracts of different Spanish wines (red and white table wines and Sherry finos). The results suggest that these determinations, associated with other analyses, would permit the chemical characterization of wines.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257318
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  • 14
    Electronic Resource
    Electronic Resource
    Trace analysis of selected benzidine and diaminodiphenylmethane derivates in urine by means of liquid chromatography using precolumn sample preconcentration, UV and electrochemical detection (1986)
    Springer
    Chromatographia 22 (1986), S. 138-146 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Benzidine+diaminodiphenyl methane derivatives ; Preconcentration from urine ; UV and electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the title compounds 4,4′-DADPM, MOCA, 3,3′-DCB, 4-ADP and 4-ADPA listing on the EPA priority pollutant list, an analytical practicable, reliable, reproducible and sensitive procedure is required. Therefore a new method has been developed for the routine determination of these toxic aromatic amines in urine at the ppb level. The quantitative determination of amines is a suitable procedure of occupationally exposed persons. Urine sample preparation is done using simple liquid-liquid extraction followed by a precolumn enrichment (PRP1-material; Hamilton). Breakthrough measurements were done using an enrichment column packed with PRP1 material. The capacities of the studied amines ranged from 21.9mg/g to 96.6mg/g, while influent concentrations differed from 28.3mg/l to 332.0mg/l. The advantages of electrochemical detection regarding to selectivity and sensitivity are clearly indicated in this paper. Separation has been achieved applying reversed-phase-high-performance-liquid chromatography (LiChrosorb RP 18/5μm) followed by electrochemical or UV-detection. The detection limits employing an electrochemical detector at a potential of 1 V range from 2.2ng to 12.1ng. UV detection at 254 nm and 280 nm is about 10–100 times less sensitive. Recoveries from spiked water samples at the 5ppb levels were 75% to 96% respectively. The standard deviation of the developed procedure varies from 5.3% to 14%. Day-to-day repeatability is good.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257315
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  • 15
    Electronic Resource
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    Non-aqueous, reversed-phase, high-performance, thin-layer chromatography and column liquid chromatography of metal complexes of porphine (1986)
    Springer
    Chromatographia 22 (1986), S. 160-164 
    Details
    ISSN: 1612-1112
    Keywords: Thin layer chromatography ; Column liquid chromatography ; 21H, 23H-Porphine ; Metalloporphyrin complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic mobility of 21H, 23H-porphine and its Ni(II), Cu(II), Zn(II) and Pd(II) complexes were investigated by high-performance thin-layer chromatography on an octadecyl-bonded, silica gel plate with various polar organic solvents including alcohols, acetonitrile, dimethylsulfoxide and propylenecarbonate. The mobility generally decreases according to the central metal ion of the complex as follows: Zn(II)〉(free porphine)〉Ni(II)〉Pd(II)〉Cu(II). Methanol is a good choice of solvent for the separation of these metal porphine complexes. Successful separation of porphine and the four metal complexes is accomplished within 13 min on a LiChrosorb RP-18 column with methanol eluent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257319
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  • 16
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    Retention prediction of polycyclic aromatic hydrocarbons in reversed phase liquid chromatography with various mobile phase compositions and column temperatures (1986)
    Springer
    Chromatographia 22 (1986), S. 13-18 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mobile phase composition and column temperature ; Retention prediction ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The relationship between the logarithmic capacity factor measured in reversed-phase liquid chromatography and the operating conditions including the mobile phase composition and the column temperature is investigated. The strategy described herein can offer the possibility to predict the retention of polycyclic aromatic hydrocarbons without any experiments and standard materials, by utilizing equations describing the relationships between retention, temperature, mobile phase composition and physicochemical properties of the solutes previously stored in the program of the microcomputer-assisted retention prediction system. This concept is one of the most promising techniques for the optimization of the separation conditions in reversed-phase liquid chromatography.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257289
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  • 17
    Electronic Resource
    Electronic Resource
    Crocheted PTFE reactors for post-column photochemistry in HPLC (1986)
    Springer
    Chromatographia 22 (1986), S. 231-234 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Post-column reactor ; Crosheted PTFE construction ; Photochemical reaction detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Construction of crocheted photochemical reactors for use in high performance liquid chromatography is described. The design of these reactors is optimal for low intensity light sources because of their cylindrical configuration. Band broadening is minimized by the use of tightly crocheted narrow bore tubing and fittings modified to reduce dead volume. These reactors are suitable for most post-column photochemical reactions with the additional possibility of serving as mixing/delay coils, deoxygenation devices for electrochemical detectors, and as low dispersion detector cells for chemiluminesckent reactions.
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    URL: http://dx.doi.org/10.1007/BF02268764
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  • 18
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    Diffusion inside particles in HPLC columns (1986)
    Springer
    Chromatographia 22 (1986), S. 319-328 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mass transfer coefficients ; Diffusion inside packing materials ; Comparison of liquid-solid and liquid-liquid systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The stationary zone mass transfer coefficient (C5) in the reduced plate height equation has been determined experimentally for an adsorption and a partition system generated on the same column. Longitudinal diffusion terms (B-terms) were measured on these systems by applying the arrested elution method. The experimentally determined C5 terms for the LLC system are 4–6 times lower than for the LSC system. B-terms for the LLC system were found to be dependent on capacity ratios and were substantially larger than the B-term for the LSC system, which turned out to be independent of capacity ratios. The obstruction factor (γip) for the intraparticle pore space was estimated by fitting the experimentally determined effective diffusion coefficients according to a mass transfer equation for packed beds. This equation was obtained by transforming a known expression for heat transfer in packed beds. Knowledge of γp allows the prediction of the magnitude of the stationary zone mass transfer (C5-term) and the comparison between the experimental and predicted values. The agreement is good in the LSC system. In the LLC system the predicted and experimental C5 values for capacity ratios up to k′=2.00 are well matched, whereas the difference becomes larger from k′=3 on. This paper explains why the efficiency of straight phase LSC systems is often substantially surpassed by analogous LLC systems.
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    URL: http://dx.doi.org/10.1007/BF02268783
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  • 19
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    New automated amino acid analysis by HPLC precolumns derivatization with fluorenylmethyloxycarbonylchloride (1986)
    Springer
    Chromatographia 22 (1986), S. 381-387 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Precolumn derivatisation ; Amino acid analysis ; Fluorenylmethyloxycarbonylchloride (FMOC)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268795
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  • 20
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    Determination of vanadium, cobalt, copper, zinc, and cadmium in biological materials by a combined anion-exchange-spectrophotometric method (1986)
    Springer
    Chromatographia 21 (1986), S. 12-15 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange ; Biological standard reference materials ; Anion-exchange preconcentration ; Thiocyanate system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A preconcentration technique involving anion-exchange in thiocyanate media has been developed for the determination of traces of bio-significant and biofunctional elements. The procedure is applied to the analyses of NBS standard reference materials as well as environmental reference materials of NIES (The National Institute of Environmental Studies, Japan Environmental Agency). The results are quoted for vanadium, cobalt, copper, zinc, and cadmium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02310587
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  • 21
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    Improved HPLC of triglycerides by special tempering procedures (1986)
    Springer
    Chromatographia 21 (1986), S. 29-36 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Single component mobile phase ; Temperature gradients ; RI-detection ; Triglyceride analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Three new methods of improving triglyceride separation by RP-HPLC using propionitrile as eluent and an RI detector are described. First the baseline was stabilized by indirect thermostating of the detector. Relatively high sensitivity adjustments (4×10−5 RI units full scale deflection) were possible allowing small fat samples to be injected (down to 200 μg). Second the increase of selectivity with decreasing temperature and the increasing sharpness of peaks at higher temperatures are shown. A high temperature is indispensible for saturated long chain compounds which tend to crystallize on the column. To fulfill this requirement and avoid loss of selectivity temperature programming has been investigated. Third at higher temperatures an additional axial temperature gradient up to 0.05 K/cm was applied to enhance peak symmetry. All chromatograms achieved by those temperature gradients show higher resolution than those obtained at constant temperatures. Butterfat could be separated into more peaks than has previously been possible. The chromatogram of soybean oil, besides showing excellent selectivity for more polar components shows a series of ten long chain compounds following POP.
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    URL: http://dx.doi.org/10.1007/BF02310591
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  • 22
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    The effect of hydrocarbon chain length and end-capping on the liquid chromatographic properties of stationary phases containing bonded nitrile groups (1986)
    Springer
    Chromatographia 21 (1986), S. 165-168 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polar stationary phases ; Chemically-modified silicas ; Alkyl-substituted phenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Stationary phases containing bonded nitrile groups have been synthesized. The effect of the n-alkyl chain length connecting the nitrile groups to the surface and of the end-capping on the chromatographic properties was studied. The synthesized material was compared with commercial nitrile phases in the separation of isomeric cresols and xylenols.
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    URL: http://dx.doi.org/10.1007/BF02311747
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  • 23
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    High-performance liquid chromatographic determination of glaucine inGlaucium flavum crantz (1986)
    Springer
    Chromatographia 21 (1986), S. 227-228 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Plant extracts ; Determination of D-glaucine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method has been developed for the extraction and rapid analysis of D-glaucine inGlaucium flavum Crantz. Simple extraction of the drug with diethyl ether was followed by high-performance liquid chromatography on a μBondapak C18 column using a mixture of acetonitrile, methanol and phosphate buffer as the mobile phase. Data on selectivity, sensitivity and precision demonstrate the reliability of this method.
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    URL: http://dx.doi.org/10.1007/BF02311892
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  • 24
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    On the chromatography mechanism of reversed-phase liquid chromatography (1986)
    Springer
    Chromatographia 21 (1986), S. 229-233 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Retention ; Selectivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An equation is derived which can describe how the retention of solutes is influenced by the composition of the mobile phase in reversed-phase liquid chromatography, the retention of solutes in alkyl bonded stationary phase regarded as the complexation between solute molecule and the active sites on the surface of the stationary phase. When the stationary phase is not fully saturated by the organic modifier, the activity of the active sites, the activity coefficient of the adsorbed solute as well as the activity coefficient of the solute in the mobile phase depend on the composition of the mobile phase. However, when the stationary phase is fully saturated, the composition of the mobile phase mainly influences the activity coefficient of the solute in the mobile phase. In addition, the selectivity of retention is discussed in terms of the derived equation.
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    URL: http://dx.doi.org/10.1007/BF02311893
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    Refractive index detection in microbore column liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 91-94 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore columns ; Refractive index detection ; Reversed-phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An existing commercial refractive index detector was modified for use with microbore column LC systems. The detector utilizes the Fresnel method. The effect of band dispersion and dilution at the detector side is of extreme importance in connection with the miniaturized LC system. In the modified model the original heat-exchanger tube was removed and a stainless steel capillary was used for heat-exchanging. Gaskets having different cell volumes were also examined with respect to band broadening and sensitivity. The detection limit was 10ng for di-n-pentyl phthalate. The examples include the detection of phthalates, alcohols, n-paraffins, and kerosine.
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    URL: http://dx.doi.org/10.1007/BF02257306
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    Liquid chromatographic retention of homologous alkanes in the two states of C18-bonded reversed phase silicas (1986)
    Springer
    Chromatographia 22 (1986), S. 103-108 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded phase structure ; Phase transition ; Homologous series
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary LiChrosorb Si100 densely grafted with octadecylmonofunctional reagents and the similar commerical LiChrosorb RP 18 have been studied in RP-HPLC, with water-methanol mobile phases at different temperatures. They exhibit a phase transition revealing two different states of bonded film as we have previously shown on densely grafted C18 or C22 macroporous silicas. The measurement of the capacity factors of the alkane homologous series indicated a discontinuity in the plot (logK′, N) at a critical number whose value is dependent on temperature. Two different forms of these curves can be observed above and below the transition, revealing the influence of bonded film state on the retention mechanism.
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    URL: http://dx.doi.org/10.1007/BF02257309
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    Matrix effect on the retention in reversed-phase liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 194-198 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Vinyl alcohol copolymer gel ; Hydrophobic interaction ; π-π interaction ; Ionic interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A polymer-based, reversed-phase column (VA-C18), prepared by grafting octadecyl chain onto vinyl alcohol copolymer gel, was investigated for its chromatographic characteristics. n-Alkanes and n-alkyl alcohols were found to be retained only by hydrophobic interaction between the solutes and the octadecyl chain. In the case of aromatic hydrocarbons, in addition to the hydrophobic interaction, π-π interaction between the solutes and the based material was elucidated to contribute to the retention. For aromatic tertiary amines which are known to strongly interact with the residual silanol group of the silica-based reversed-phase columns to produce broadened and skewed peakes, the VA-C18 column also retained these substrates strongly by the combination of hydrophobic, π-π, and ionic interactions. In this case, however, symmetrical peaks were observed. From these results, it was determined that in the case of VA-C18, the base material was found not to produce undesirable effect although the solutes interact with the base. Further conclusion obtained was that in reversed phase liquid chromatography, chromatographic properties of base matrix is highly responsible for the overall retention.
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    URL: http://dx.doi.org/10.1007/BF02257327
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    Synthesis and evaluation of selective reversed phase packing materials for HPLC (1986)
    Springer
    Chromatographia 21 (1986), S. 392-396 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded phases ; Specific selectivity ; Polynuclear aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for preparing selective phases for reversed phase chromatography is described. Five different polymeric modified silica gel phases were prepared by simultaneously bonding with silanes, the first phase one line is missing according to the manuscript should read: the first phase being modified with ODS. Modification of the other four phases was achieved by treatment with ODS and cyanopropyl- or cyanodecyl-trichlorosilane, thus yielding reversed phase materials of different properties. The chromatographic selectivity of each phase was demonstrated by elution of a number of standard mixtures containing polyaromatic compounds. The selectivity is described with respect to carbon load and the ODS/CN-ratio of the stationary phase for these compounds. Different PAHs are influenced to a greater or lesser degree. Through introduction of various functional groups in the network of C18 chains of a polymeric modified silica gel, it is possible to design columns with specific selectivities.
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    URL: http://dx.doi.org/10.1007/BF02346138
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    Elution characteristics of polymeric solutes and inorganic salts in HPLC on a cellulose acetate column (1986)
    Springer
    Chromatographia 22 (1986), S. 341-344 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Size-exclusion chromatography ; Cellulose acetate packing ; Polymer separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The elution characteristics of polymeric solutes or inorganic salts in high-performance liquid chromatography were examined with a cellulose acetate column using water as the mobile phase. Polymeric (PVP, PEG, etc.) and ionic solutes eluted in a shorter time than deuterium oxide. The retention times for polymers decreased continuously as the molecular weight increased. The elution characteristic, of polymers is assumed to be affected mainly by size exclusion effect. The retention times for ionic solutes increased with the concentration of the injected solutions and asymptotically approached some constant values. The retention times were also affected by the valence and/or hydration of the ion. It was suggested tha the exclusion of ionic solutes was caused by electric repulsion and/or hydration of ion. It was recognized that the salts which were excluded more strongly were rejected more effectively by cellulose acetate membrane in reverse osmosis. HgCl2 which is not dissociated in aquous solution was observed to be adsorbed strongly on cellulose acetate.
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    High-performance liquid chromatographic measurement of 8-methoxypsoralen in plasma (1986)
    Springer
    Chromatographia 21 (1986), S. 443-446 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; 8-Methoxypsoralen ; Drug monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple high-performance liquid chromatographic method for the measurement of 8-Methoxypsoralen (8-MOP) in human plasma following a single 40mg dose has been described. After addition of phosphate-NaOH buffer, pH 12, and internal standard (trimethylpsoralen), the sample is vortex-mixed with diisopropylether. The resulting extract is analysed on a reverse phase column using phosphoric acid (0.05% v/v): acetonitrile (1:1) as mobile phase, and U.V. detection at 220nm. No interference from endogenous sources has been observed. The limit of sensitivity of the assay is 5ng/ml plasma. The measuring range is between 10–700ng 8-MOP/ml plasma, to be expected from oral doses of 0.6mg 8-MOP/kg body weight, and corresponds to the therapeutic plasma concentration. The relative standard deviation at 50ng/ml level of 8-MOP is 3.6%.
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    URL: http://dx.doi.org/10.1007/BF02341267
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    Validierung und Kalibrierung in der HPLC (1986)
    Springer
    Chromatographia 22 (1986), S. 373-378 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Validation ; Calibration ; Peak purity ; Confidence and prediction intervall
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Zusammenfassung Die Validierung einer HPLC-Methode umfaßt eine ganze Reihe von Punkten, von denen hier auf zwei eingegangen wird: Peakreinheit und Kalibrierung. Die Validierung einer Trennung ist für eindimensionale Detektoren (UV, RI, ECD u.a.) praktisch nur aus der Peakform möglich. Drei Wege werden aufgezeigt: die Gesetzmäßigkeit der Halbwertsbreite, der Einsatz der Ableitungs-Chromatographie und die Abhängigkeit des Symmetriefaktors von der relativen Peakhöhe. Bei mehrdimensionalen Detektrren (Photodiodenarry im UV) können spektrale Parameter als Absorptionsverhältnis (ratio), Differenzspektroskopie (peak suppression) oder auch ein direkter Spektrenvergleich zusätzlich ausgewertet werden. Bei der Validierung einer Kalibrierung werden die wichtigsten Möglichkeiten wie Vertrauensbereich der Kalibrierfunktion, Voraussageintervall und Vertrauensbereich des analytischen Ergebnisses mit entsprechenden Gleichungen angegeben. Diskutiert wird auch die erreichbare Präzision bei der Methode des externen Standards.
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    Separation of ribosomal protein-protein crosslinks fromBacillus stearothermophilus and ribosomal proteins from archaebacteria by high performance liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 249-254 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase operation ; Ribosomal proteins ; Methanococcus vannielii ; Bacillus stearothermophilus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High performance liquid chromatography was used to separate proteins derived from ribosomes of the archaebacteriumMethanococcus vannielii. Several methods of separation were tested: size exclusion chromatography, reversed phase and ion-exchange chromatography. Best results were obtained using reversed phase columns and volatile buffers that allow direct sequence analysis of the proteins. In addition, HPLC was used to separate crosslinked protein-protein pairs fromBacillus stearothermophilus ribosomes on a preparative scale. Identification of crosslinked amino acids is a prerequisite for more detailed topographical investigations of this cell organelle. The purification of the 50S crosslink L23–L29 was achieved by a combination of two different reversed phase columns, and the 30S crosslink S13–S19 was purified after salt extraction by size exclusion chromatography. The methods described here allow a rapid preparation of ribosomal proteins for structural and functional investigations.
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    Determination of ten anti-inflammatory drugs in serum by isocratic liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 187-188 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anti-inflammatory drugs ; Extraction from serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high performance liquid chromatographic system has been developed for the resolution of ten anti-inflammatory drugs. Isocratic separation was achieved using a Spherisorb 5μm ODS column with an eluent consisting of water-orthophosphoric acid to pH 3.2: acetonitrile: methanol (52∶35∶13). A comparison was made between chloroform/acetonitrile (3∶2) and hexane/ether (1∶1) as solvents for the extraction of these drugs from serum.
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    Remarks on the detection of phenols in airborne particulate matter (1986)
    Springer
    Chromatographia 22 (1986), S. 191-193 
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    ISSN: 1612-1112
    Keywords: Gas chromatography/mass spectrometry ; Column liquid chromatography ; Phenols ; Suspended particulate matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Samples of suspended particulate matter collected in Duisburg were investigated for phenolic compounds. The loaded filters were extracted with dichloromethane for 10 hours in a soxhlet apparatus. The concentrated extract was resolved in cyclohexane and separated into a non polar and a polar fraction on alumina. The polar fraction was taken up in dichloromethane and steam-distilled. The distillate was extracted with ether. After the evaporation of the ether, the residue was resolved in dichloromethane and allowed to react with benzoyl chloride. After adding toluene the solution was reduced in volume and analyzed in a GC-MS system. For the separation of phenols by means of HPLC the enrichment of the phenols was performed without benzoylization. Six phenols were detected: hydroxibenzene, methylhydroxibenzene, hydroxibiphenyl, hydroxifluorene, benzylhydroxibenzene and dihydroxibiphenyl.
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    Liquid chromatographic separation of metal ions on several silica-bound chelating-agent stationary phases (1986)
    Springer
    Chromatographia 22 (1986), S. 5-12 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Metal-ion separation ; Bonded ; Chelating phase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of metal-ions on several new silica-bound azo-coupled chelating stationary phases is described. Retention on 2-methyl-8-quinolinol and N-(1-naphthyl)-ethylenediamine phases is in the order of known homogeneous-solution stability constants. Very short retention times were obtained on the 2-methyl-8-quinolinol phase compared to an 8-quinolinol phase. A reversed order of retention was observed on β-diketone and dithizone stationary phases in tartrate mobile phase. Two different mechanisms of metal-column interaction appear to occur. Large pH and mobile-phase buffer concentration effects were exhibited, especially by the diketone and dithizone phases. An excellent separation of a six-metal mixture is demonstrated on a dithizone column.
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    HPLC separation of flavonol glycosides in wines (1986)
    Springer
    Chromatographia 22 (1986), S. 268-270 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase isocratic elution ; Flavonol glycosides ; Wine phenolics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Isocratic elution from a reversed-phase high performance liquid chromatographic column was used to separate several flavonol glycosides of wines after a preparative isolation which includes column, paper and thin-layer chromatographic procedures. The method has been applied to the separation and identification of flavonol glycosides in wines from different regions in Spain.
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    Model for partition chromatography of ionic solutes in the presence of eluent electrolytes (1986)
    Springer
    Chromatographia 22 (1986), S. 261-267 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Partition ; Ionic solutes ; Counter-ion effect ; Co-ion effect
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A general model that does not depend upon a specific mechanism is proposed for describing the retention of ionic solutes in partition chromatography in the presence of electrolytes. The effect of various types of 1∶1 and 1∶2 eluent electrolytes on the retention of inorganic ions on a cross-linked polyacrylamide is successfully explained in terms of the model. Capacity factors of ionic solutes can be estimated semiempirically on the basis of the theoretical equation presented.
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    Evaluation of various bonded-phase materials for the off-line clean-up procedure of urinary 5-hydroxyindolacetic acid prior to its determination by HPLC (1986)
    Springer
    Chromatographia 22 (1986), S. 299-302 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phases ; Off-line prepurification ; Urinary 5-hydroxyindolacetic acid ; Electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Determination of serotonin (5-hydroxytryptamine, 5-HT) and its main metabolite, 5-hydroxyindolacetic acid (5-HIAA), became important in clinical chemistry. Commercially available and newly synthetised bonded-phase materials were evaluated in the off-line clean-up procedure of urine samples prior to the determination of 5-HIAA by high-performance liquid chromatography using electrochemical detection. From the point of reproducibility and recovery the best results were obtained employing our newly synthetised material consisting of silica gel support with wide pore diameter (≥20 nm) and large pore volume (≥2.5 cm3 g−1) with a mean (B.E.T.) surface area of 196m2 g−1. It has been modified by mixed chemically bonded C16−C18 phase. The achieved surface carbon coverage was 14.7% C.
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    HPLC analysis of phenylthiocarbamyl (PTC) amino acids II. Application in the analysis of (poly)peptides (1986)
    Springer
    Chromatographia 22 (1986), S. 351-357 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenylthiocarbamyl amino acids ; Gas-phase hydrolysis ; Comparison of HPLC data with classical amino acid ; analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The composition of 10 known (poly)peptides of widely different nature was determined by a previously optimized HPLC-PTC amino acid analysis; for the gasphase hydrolysis and the derivatization step use was made of a Pico-Tag Workstation. Results are in good agreement with those of the classical Moore and Stein technique. Strong points of the new method are its sensitivity which is in the low pmol range (nmol for the classical procedure), and its ease of use. The complete procedure can be carried out within one working day by applying an accelerated hydrolysis step. Finally, the (gas-phase) hydrolysis time of peptides containing IIe/Val sequences could be reduced to 24 hours when hydrolysis was carried out at a higher temperature.
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    The gradient volume principle for fast evaluation of optimum conditions for isocratic analysis (1986)
    Springer
    Chromatographia 22 (1986), S. 31-39 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gradient elution ; Isocratic elution ; Prediction of optimum isocratic ; Conditions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper describes by simple experiments in a pragmatical way by easy rules of thumbs gradient optimization. Besides selection of the stationary phase and initial and final conditions the two other important variables are program time and eluent flow rate. It is demonstrated, that when the product of both, the gradient volume, is kept constant, the solutes are always eluted with the same eluent composition at column outlet. At constant gradient volume, peak broadening depends on flow rate and on the eluent properties (viscosity) at which the solutes elute, and on the time the solutes spend in the column. Because peak broadening increases with increasing gradient volume, the peak capacity in gradient elution shows an optimum at gradient volumes around 15 empty column volumes (program times 45 to 60 min at flow rates of 1 ml/min with standard columns). Gradient elution can also be used for fast evaluation of optimum eluent composition for isocratic analysis. This procedure requires a calibration of the equipment for determination of eluent composition at column outlet. The sample is chromatographed in a standard gradient run of 10 to 15 empty column volumes. The eluent composition at which the solute of interest elutes during the gradient is used for isocratic analysis, where the k' value of this solute will then be around 2.
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    Relationship between retention and molecular structure of pyrimidine bases (1986)
    Springer
    Chromatographia 22 (1986), S. 73-76 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pyrimidines ; Bonded stationary phases ; Structural groups increments in retention
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The influence of the type and position of CH3, NH2 and OH groups in the pyrimidine ring, the eluent composition and the surface chemistry of the stationary phase on the retention of pyrimidine bases in reversed-phase liquid chromatography was investigated. On the basis of the hypothesis about the additivity of the adsorption energy the contribution of various structural groups on retention has been established.
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    A high-performance liquid chromatographic method for the measurement of amiodarone and its main metabolite (desethylamiodarone) in plasma samples from patients treated withCordarex ® (1986)
    Springer
    Chromatographia 22 (1986), S. 135-137 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Amiodarone ; Desethylamiodarone ; Silica cartridge isolation ; Drug monitoring
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A procedure for the rapid, quantitative isolation of amiodarone and its main metabolite (desethylamiodarone) from plasma with SEP-PAK™ silica cartridges is described together with a sensitive high performance liquid chromatographic assay for the quantitative determination of the drugs. The recovery of amiodarone and its metabolite was greater than 80% over an investigated range of 0.1–5μg/ml of plasma and the limit of quantitation by the assay was 50 ng/ml of plasma. The column extraction of amiodarone and its metabolite coupled with the chromatographic versatility of the method make it suited for either detailed pharmacokinetic studies and routine plasma analysis of amiodarone.
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    Poly(vinylpyrrolidone)-coated silica: A versatile, polar stationary phase for HPLC (1986)
    Springer
    Chromatographia 21 (1986), S. 573-582 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polyvinylpyrrolidone-coated silica gel ; Separation of polar compounds ; Separation of proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Poly(vinylpyrrolidone) (PVP) is immobilized on both, small- and large-pore silicas by thermal treatment, γ-radiation, or peroxide initiated polymerization. The hydrolytic stability of such a highly polar stationary phase significantly exceeds that of a comparable phase prepared by the chemical reaction of silica with a pyrrolidone ethyl dimethylchlorosilane silanization reagent. The properties of the different PVP-silicas are evaluated by elemental analysis, spectroscopy, and chromatography. Columns of PVP-silica packings can be used in several modes: a) under normal-phase conditions as a polar bonded stationary phase, b) under reversed-phase conditions, for the separation of organic proton-donor and hydrogen-bonding compounds, c) for the aqueous size exclusion chromatography of proteins, and d) with salt gradients for the hydrophobic interaction chromatography of proteins. The minimum observable reduced plate-height of PVP-silica columns is about 3. Double-layer polymer coating experiments using PVP-silica covered with poly(methyloctadecylsiloxane) have been performed to study diffusion and shielding effects of different polymer layers in the stationary phase. Depending on separation conditions, one or the other polymer governs the retention process. A mixed selectivity was observed in a reversed phase mode with acidic eluents.
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    Separation of hordein proteins from european barley by high-performance liquid chromatography: Its application to the identification of barley cultivars (1986)
    Springer
    Chromatographia 21 (1986), S. 49-54 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase ; Ion-exchange ; Barley proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography using either reversed phase or anion-exchange techniques was used for the fractionation of hordein proteins extracted from European barley. A reversed phase method is presented which utilises an Ultrapore column packed with a wide pore (30 nm) C-3 alkylbonded silica support. Using this method up to 20 components may be separated in 54 min. Elution profiles were found to be reproducible. A further method using rapid anion-exchange chromatography indicated that up to 13 components may be separated, a number which is comparable to that found with electrophoresis. The separation of proteins extracted from different barley cultivars indicated that on the basis of elution profiles high-performance liquid chromatography using either reversed phase or anion-exchange offers considerable potential as a method for barley cultivar identification.
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    The determination of lactate, acetate, chloride and phosphate in an intravenous solution by non-suppressed ion chromatography (1986)
    Springer
    Chromatographia 21 (1986), S. 648-650 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Non-suppressed ; Ion Chromatography ; Intravenous solutions ; Acetate, lactate, chloride and phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The determination of acetate, lactate, chloride and phosphate in an intravenous solution is investigated using non-suppressed ion chromatography with indirect UV absorption detection. When phthalate eluents are used with low capacity anion-exchange columns, the above solute species cannot be resolved unless acetonitrile is added to the eluent. Optimum results are obtained with 0.3 mM phthalate (pH 6.0) containing 30% acetonitrile as eluent. The improved resolution with this eluent is attributed to the existence of a partial reversed-phase retention mechanism operating on the unfunctionalised portions of the styrene-divinylbenzene polymeric ion-exchange material.
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    URL: http://dx.doi.org/10.1007/BF02311921
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    Purification of CIS-trimedlure isomers by high-performance liquid chromatography (1986)
    Springer
    Chromatographia 21 (1986), S. 651-654 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Separation of isomers ; Trimedlure ; Medfly ; Ceratitis capitata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatographic procedures were developed to make it possible to obtain the fourcis-trimedlure isomers (V, W, X, and Y) in pure form. Trimedlure-V and-Y were each readilt separated from the four-componentcis-trimedlure mixture through high-performance liquid chromatographic analysis on 5-μm and 3-μm silica, but trimedlure-W and-X were not adequately resolved. Chromatography of 5-μm silica of the mixtures obtained by epimerization of thetrans-trimedlure isomers, C and B2, yielded the respective epimers, trimedlure-W and-X, in pure form.
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    URL: http://dx.doi.org/10.1007/BF02311922
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    Cellulose conformation responsible for resolution of DL-amino acids (1986)
    Springer
    Chromatographia 21 (1986), S. 79-82 
    Details
    ISSN: 1612-1112
    Keywords: Thin-layer chromatography ; Column liquid chromatography ; Cellulose conformation ; Hydrophobicity ; DL-amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary For the purpose of biochemical study, the resolution of non-derivatized DL-amino acids was carried out by using native-cellulose thin-layer and column chromatography. Its resolution capability was known to be in proportion to the increase of environmental hydrophobicity. It is suggested that the resolutions of DL-amino acids might be resulted from the cellulose conformation change under hydrophobic conditions. The model structures of cellulose are proposed in order to understand the mechanism of chiral selection of amino acids on its molecular surface.
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    URL: http://dx.doi.org/10.1007/BF02311680
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    Triacetylcellulose on silica compared with non-dilute triacetylcellulose I as a high-performance liquid chromatographic sorbent (1986)
    Springer
    Chromatographia 21 (1986), S. 223-226 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Triacetylcellulose on silica ; Triacetylcellulose, non-dilute ; Enantiomers ; X-ray diffraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Triacetylcellulose coated on silica is a novel HPLC sorbent introduced for the separation of enantiomers. A comparison of enantioselectivities α, and resolutions R5 of this material with known pure triacetylcellulose I shows considerable differences. From X-ray wideangle diffraction it is suggested that the novel sorbent also consists of the triacetylcellulose modification I, but its degree of crystallinity is probably lower than that of the non-dilute sorbent. The advantages of the two stationary phases are discussed.
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    URL: http://dx.doi.org/10.1007/BF02311891
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    Optimization of stepwise gradient elution in reversed-phase chromatography (1986)
    Springer
    Chromatographia 21 (1986), S. 259-264 
    Details
    ISSN: 1612-1112
    Keywords: Reversed-phase chromatography ; Column liquid chromatography ; Isocratic elution ; Optimization of stepwise elution ; Chloro- and methylphenols
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Equations describing multi-step gradient elution with a mobile phase of constant composition in each step were derived. These equations useful for calculating the retention volumes in both gradient HPLC and TLC were derived on the basis of the relationship between the isocratic capacity factor and the volume fraction of the organic modifier. The validity of the equations was experimentally verified in a LiChrosorbRP-18-water/methanol system for 11 methyl- and chlorobenzenes and phenols. A satisfactory agreement between the theoretical and experimental k′ values was found.
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    URL: http://dx.doi.org/10.1007/BF02311878
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  • 50
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    A microcomputer-assisted retention prediction with gradient elution in reversed-phase liquid chromatography (1986)
    Springer
    Chromatographia 21 (1986), S. 541-545 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Retention prediction ; Reversed phase gradient elution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In order to improve computer optimization techniques in liquid chromatography such as the Simplex methods, an alternative approach using retention prediction based on quantitative structure-retention relationships studies is proposed for gradient elution in the reversed-phase separation mode. With physico-chemical parameters of the solutes used as the descriptors, the microcomputer-assisted system can predict their retention within 10% relative error under the appropriate experimental conditions. In this process, no pure substances are required to predict their retention.
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    URL: http://dx.doi.org/10.1007/BF02310543
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    High-performance liquid chromatography separation of chlordecone and its metabolites (1986)
    Springer
    Chromatographia 22 (1986), S. 165-167 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Kepone and its metabolites ; Chlordecone ; Kepone metabolites ; Pesticide analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High-performance liquid chromatography (HPLC) was used to separate chlordecone (Kepone), and two of its metabolites, hydrochlordecone and dihydrochlordecone. Elution of the three peaks occured after the solvent concentration reached 100% methanol and was maintained at 100% for approximately five minutes. The method was linear for chlordecone in the concentration range of 10 to 100 μg.
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    URL: http://dx.doi.org/10.1007/BF02257320
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    HPLC determination of carotenoids in human serum by gradient elution technique (1986)
    Springer
    Chromatographia 22 (1986), S. 189-190 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Serum carotenoids ; Amino-cyano stationary phases ; Gradient Elution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Polarities of the carotenoids in human serum are very different; many nonpolar carotenoid hydrocarbons (e.g. β-carotene, lycopene) and highly polar hydroxycarotenoids (e. g. β-cryptoxanthin, zeaxanthin, lutein) can be found among them. Gradient elution chromatography was used for the separation of β-carotene, lycopene, β-cryptoxanthin, lutein and zeaxanthin in serum samples applying amino and cyano packings (Chromsil-NH2, Chromsil-CN). The effects of different stationary phases on the selectivity were compared. The method is particularly suitable for the direct determination of serum levels of carotenoid in serum extracts.
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    URL: http://dx.doi.org/10.1007/BF02257325
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    Separation of metal ions using in-situ complexation chromatography with ethyl xanthate and 1,10 phenanthroline as ligands (1986)
    Springer
    Chromatographia 22 (1986), S. 275-277 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Separation of metal ions ; Formation of complexes ; Ethyl xanthate ; 1,10-Phenanthroline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary On-column adduct formation has been used to enhance the stability of metal xanthate complexes. useful metal xanthate separations have been achieved by including 1,10 phenanthroline in the chromatographic eluent along with the primary complexing agent.
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    URL: http://dx.doi.org/10.1007/BF02268773
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    Interference of chloride in the speciation of arsenic by ion chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 292-298 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion chromatography ; Arsenic speciation ; Chloride interference ; Urine-seawater samples
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The presence of high concentrations of chloride in urine and seawater samples interferes with the separation of arsenic species by ion chromatography; single peaks may be split into two or more discrete peaks, as a result of the large differences in the ionic strengths of the mobile and injection solvents. A simple model is proposed to explain this phenomenon.
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    URL: http://dx.doi.org/10.1007/BF02268777
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    Use of diluted anion-exchange and hydrophobic properties in separating synthetic single-stranded oligodeoxyribonucleotides on mixed-ligand stationary phases (1986)
    Springer
    Chromatographia 21 (1986), S. 402-408 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Mixed-interaction stationary phases ; Oligodeoxyribonucleotide separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Mixed-ligand or “mixed-interaction” stationary phases are composed of bonded silanes possessing both ionic and hydrophobic character. The complex retention properties exhibited by these phases have been particularly useful in separating large biomolecules, such as synthetic single-stranded oligodeoxyribonucleotides. By isolating the individual properties of separate ligands present in mixed-ligand stationary phases a better understanding of the heterogeneous surface was sought. Specifically a dilute anion-exchange mixed-ligand phase of 5% surface coverage showed dramatically different selectivity for oligomers compared to hydrophobic stationary phases. Of particular interest was the increased selectivity observed in separating oligonucleotides differing on the 3′ end over conventional reversed-phases supports.
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    URL: http://dx.doi.org/10.1007/BF02346140
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    HPLC analysis of phenylthiocarbamyl (PTC) amino acids. I. Evaluation and optimization of the procedure (1986)
    Springer
    Chromatographia 22 (1986), S. 345-350 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Phenylthiocarbamyl amino acids ; Pre-column derivatization ; Gas-phase protein hydrolysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An HPLC system has been developed in which 23 phenylthiocarbamyl (PTC) amino acids are distinctly separated. Applying this system, the preceding steps in HPLC amino acid analysis i.e. gas-phase hydrolysis of the protein/peptide sample and the pre-column derivatization, were evaluated and optimized. PTC amino acids in HPLC buffer solution are stable for at least 16 hours if stored at 5°–8°C. The sensitivity of the method is in the low pmol range.
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    URL: http://dx.doi.org/10.1007/BF02268788
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    Low temperature liquid chromatographic separation of oxygenated terpenes from terpene hydrocarbons (1986)
    Springer
    Chromatographia 21 (1986), S. 478-479 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Silica gel columns at low temperatures ; Terpene hydrocarbons ; Oxygenated terpenes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The separation of β-pinene and menthone by HPLC on a silica gel column can be significantly improved with decreasing the column temperature. On a perparative scale complete separation of oxygenated terpenes from terpene hydrocarbons could be carried out under such conditions.
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    URL: http://dx.doi.org/10.1007/BF02341274
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    On-line post-column extraction in column liquid chromatography with electron-capture detection (1986)
    Springer
    Chromatographia 22 (1986), S. 235-240 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase system ; On-line post-column extraction ; Electron-capture detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A post-column extraction module has been used for the on-line coupling of conventional-size (4.6mm i.d.) reversed-phase liquid chromatography (PPLC) and electron-capture detection (ECD). Hexane and toluene were used as extraction solvents, while methanol turned out to be preferable to dioxane and acetonitrile as modifier in the aqueous eluent. In this system the ECD behaves as a concentration-sensitive detector. The band broadening in the evaporation interface, which connects the extraction module with the ECD, dominates the total post-column band broadening; it can be reduced to 3–4 sec by directing at least 0.25–0.30 ml/min (i.e. 25–30%) of the extraction solvent to the ECD. Optimal signal-to-noise ratios were observed if 30–60% of the extraction solvent is directed to the ECD. The noise levels are 5–10 times higher than in systems using a direct coupling of normal-phase LC or narrow-bore reversed-phase liquid chromatography to the ECD. Separations of phenylurea herbicides and chlorophenols demonstrate the applicability of the RPLC-extraction module-ECD system.
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    URL: http://dx.doi.org/10.1007/BF02268765
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    Mixed mode chromatography via column switching for the simultaneous HPLC analysis of lonic and non-lonic nucleic acid constituents (1986)
    Springer
    Chromatographia 21 (1986), S. 317-320 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Column switching ; Ion-exchange and reverse phases ; Nucleic acid constituents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is presented for the separation of purine and pyrimidine nucleotides, nucleosides and bases in one analysis. This method uses both the ion-exchange and the reversed-phase modes for the analysis of these compounds. The modes are coupled through automatic switching valves. The use of these valves permits the isolation of either column during the analysis. The nucleotides are separated on an anion-exchange column and the nucleosides and bases on a C-18 column. Total analysis time is approximately one hour, and a very small volume of a sample can be analyzed. The technique is flexible and mobile phase conditions for one column can be altered without affecting the resolution on the other column. The method is applicable to biological matrices.
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    URL: http://dx.doi.org/10.1007/BF02311602
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    Remarks on the detection of aza arenes in airborne particulates (1986)
    Springer
    Chromatographia 21 (1986), S. 327-330 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography/mass spectrometry ; Aza arenes ; Suspended particulate matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Suspended particulate matter sampled in the ambient air of Duisburg was investigated for the content of aza heterocyclic compounds. The loaded filters were extracted for 10 hours in a soxhlet apparatus. The concentrated extract was shaken with diluted sulphuric acid. The aqueous layer was adjusted to pH 12 with potassium hydroxide and then extracted with dichloromethane. The organic layer was transfered into cyclohexane and columned on alumina. The separated fraction was then examined by means of GC/MS. Quinoline, benzoquinoline, acridine and some of their alkyl derivates as well as azapyrene/fluoranthene were identified, whereas benzo- and dibenzoacridine could not be detected.
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    URL: http://dx.doi.org/10.1007/BF02311604
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    Effects of stationary-phase polarity on retention in reversed bonded phase HPLC columns (1986)
    Springer
    Chromatographia 21 (1986), S. 335-341 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Stationary phase polarity ; Cyano-silica ; Phenyl-silica ; Polar group selectivities of organic modifiers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Variations in retention and selectivity have been studied in cyano, phenyl and octyl reversed bonded phase HPLC columns. The retention of toluene, phenol, aniline and nitrobenzene in these columns has been measured using binary mixtures of water and methanol, acetonitrile or tetrahydrofuran mobile phases in order to determine the relative contributions of proton donor-proton acceptor and dipole-dipole interactions in the retention process. Retention and selectivity in these columns was correlated with polar group selectivities of mobile phase organic modifiers and the polarity of the bonded stationary phases. In spite of the prominent role of bonded phase volume and residual silanols in the retention process, each column exhibited some unique selectivities when used with different organic modifiers.
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    HPLC analysis of the large polycyclic aromatic hydrocarbons in a diesel particulate (1986)
    Springer
    Chromatographia 21 (1986), S. 439-442 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Photodiode array detection ; Diesel particulate extract ; Large polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary High performace liquid chromatography (HPLC) was used to separate the large polycyclic aromatic hydrocarbons in a diesel particulate extract. Identification of individual peaks was made using a photodiode array UV/visible detector to collect their absorbance spectra. Comparisons between standard compounds and the peaks were made using both retention times and spectra. Compounds of up to 10 rings were identified.
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    Thiophenepropyltrichlorosilane as chemical modifier on silicagel for reversed phase chromatography (1986)
    Springer
    Chromatographia 21 (1986), S. 451-453 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase separations ; Thiophene silane ; Polynuclear aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Modification of silica gel with thiophene-propyl-trichlorosilane is described as well as the synthesis of the silane. The chromatographic performance and selectivity are demonstrated with various polyaromatic compounds. Thiophene-modified silica gel was found to exhibit a selectivity comparable with both ODS-and amino-phases.
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    URL: http://dx.doi.org/10.1007/BF02341269
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    Retention behaviour in micro-HPLC on various types of glasses modified with phenyl groups (1986)
    Springer
    Chromatographia 21 (1986), S. 467-472 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Bonded stationary phases ; Phenyl-modified glasses ; Antiepileptic drugs
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention and selectivity behaviour of some antiepileptic drugs were studied by micro high-performance liquid chromatography on nine types of phenyl-modified glasses, prepared with xylene solution containing phenyldimethylchlorosilane (P), diphenylmethylchlorosilane (D) or triphenylchlorosilane (T), using three types of glass with various mean pore diameters and/or specific surface areas. From elemental analysis data for carbon, the maximum number of accessible phenyl surface groups per 100Å2 of glass (mean pore diameter: 335Å, specific surface area: 69m2/g) in P, D and T gel was calculated to be 2.38, 1.58 and 0.76, respectively. Using various CH3CN−0.01 M KH2PO4 mixtures as eluents, the antiepileptic drugs were separated on all the glasses studied, but with different degrees of resolution. With an increase in the specific surface area, the k′ values of some antiepileptic drugs also increased.
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    On-line deproteinization of serum sample for HPLC analysis of hydrophilic compounds and its application to gentamicin (1986)
    Springer
    Chromatographia 21 (1986), S. 519-522 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; On-line deproteinization ; Butyl Toyopearl 650-M ; Gentamicin in serum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The binding of serum proteins with Butyl Toyopearl (BT) 650-M has been investigated and applied to on-line deproteinization for the HPLC determination of gentamicin components, c1, c1a, c2, in serum. It was found that in 0.4% perchloric acid medium about 36mg of BSA was adsorbed on 1ml of wet gel. Under this condition hydrophilic components such as gentamicin passed through the pre-column packed with BT 650-M, while serum proteins and hydrophobic components were trapped in the pre-column. The ion pair between gentamicin components and pantanesulfonate anion was effectively trapped in a reversed-phase analytical column. It was then eluted and fluorometrically determined by post-column derivatization with o-phthalaldehyde. The recovery was quantitative with good reproducibility at therapeutic concentrations in sera. Several clinical samples were analyzed by the method.
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    URL: http://dx.doi.org/10.1007/BF02310539
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    Reversed phase liquid chromatographic assay of FLA 908, a metabolite of remoxipride, in hydrolysed urine by means of a peak compression effect (1986)
    Springer
    Chromatographia 22 (1986), S. 283-286 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair chromatography ; Peak compression ; Remoxipride metabolite ; Conjugate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary FLA 908 was identified as a metabolite of remoxipride in human urine after enzymatic hydrolysis. The identity was proven by comparison of its retention time in LC and its UV and mass spectra to authentic FLA 908. The concentration of FLA 908 in human urine was determined using chromatographic conditions where a peak compression effect was obtained. This effect, giving an extremely narrow peak for FLA 908, made it possible to determine low concentrations of the compound in enzymatically hydrolyzed urine. The limit of quantitation was improved more than by a factor of 5 compared to conventional chromatography and the precision was good with a coefficient of variation of 〈5%. Less than 1% (0.44–0.91%) of the administered remoxipride dose was found to be excreted as conjugated FLA 908 while only trace amounts (≤0.01%) of nonconjugated FLA 908 were seen.
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    URL: http://dx.doi.org/10.1007/BF02268775
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    Isolation of standard-, deoxy- and highly phosphorylated nucleotides fromBacillus brevis and their separation by ion-pair high-performance liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 287-291 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ion-pair reversed-phase HPLC ; Nucleotides ; Highly phosphorylated nucleotides ; Bacillus brevis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is presented for the separation of standard and deoxynucleotides as well as of ppGpp, pppGpp, ApppA and AppppA using reversed-phase ion-pair high-performance liquid chromatography with a pH and salt gradient. Formic acid extracts fromBacillus brevis give about 50 well resolved peaks in one run. Studies on the recovery of the identified nucleotides have been carried out.
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    URL: http://dx.doi.org/10.1007/BF02268776
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    A gradient valve for HPLC (1986)
    Springer
    Chromatographia 22 (1986), S. 316-318 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pumping system ; Low pressure mixing ; Gradient elution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A novel concept of a low-pressure single gradient mixing pump is described. The solvents are mixed via a two-way switching valve of special design. Due to a mechanical transmission between the pump piston and the gradient valve rotor, the precise partitioning of the both liquids is achieved regardless of a nonlinear piston refill period. The use of this concept has no limitations for specially constructed pumps equipped with stepping motors and with position encoders for piston displacement. For isocratic elution with mixed solvents it is possible to set manually any binary composition without the need of any additional accessory.
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    URL: http://dx.doi.org/10.1007/BF02268782
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