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  • Column liquid chromatography  (122)
  • ASTROPHYSICS
  • Data analysis / ~ processing
  • Industrial Chemistry
  • Inorganic Chemistry
  • NOISE
  • Seismology
  • ddc:330
  • Springer  (123)
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  • 1985-1989  (124)
  • 1950-1954
  • 1987  (56)
  • 1986  (68)
  • 1
    Electronic Resource
    Electronic Resource
    An efficient procedure for extraction and determination of steroids in the tissue of laboratory animals (1987)
    Springer
    Chromatographia 23 (1987), S. 796-802 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Steroids ; Rat tissue ; Purification by extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatographic method for analysis of steroids in the tissue of laboratory animals is described. A two-stage solid extraction procedure, utilizing Sep-pak C18 and graphitized carbon black, gives a purified product. Steroids in this extract were separated by multistep gradient elution with a reversedphase liquid chromatography system, using acetonitrilewater as solvent. Several columns with different geometry and phase loading were investigated. Optimum resolution was obtained with a medium covered and spherical particle. The applicability of this method was successfully demonstrated in the analysis of the testis and adrenal gland of rat.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311402
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  • 2
    Electronic Resource
    Electronic Resource
    HPLC of aminoacids on silica coated with ammonium tungstophosphate (1987)
    Springer
    Chromatographia 23 (1987), S. 814-817 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin layer chromatography ; Ammonium tungstophosphate ; Aminoacids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of aminoacids on columns of silica coated with different percentages of ammonium tungstophosphate at several buffer phosphate concentrations is reported. The stationary phase shows a high selectivity towards aminobutyric acids and methyl derivatives of tryptophan due to the distance between the carboxylic group and the −NH 3 + group involved in the cation-exchange process and/or to the steric hindrance by a methyl substituent. A relationship between HPLC and HPTLC data has been verified and applied to the prediction of the separation of six aminoacids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311405
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  • 3
    Electronic Resource
    Electronic Resource
    Limits of determination and calibration in HPLC (1987)
    Springer
    Chromatographia 23 (1987), S. 934-938 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Calibration ; Confidence interval ; Limit of determination ; Limit of calibration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In HPLC calibration the expressions lowest calibration limit and determination limit are defined in statistical terms. The lowest calibration limit is the minimum mass in the measured series of calibration points. It is calculated from the confidence interval of the inverse of the calibration function as the lowest mass limit that may be differentiated from zero mass with a preset probability of error. If the calculated lowest calibration limit is lower than the actual data, points at lower concentration may be measured. The determination limit is the smallest concentration of an analysis that is differentiated from the concentration zero or an apparent blind value in the calibration curve with a given probability of error. Using two different UV-detectors (variable wavelength and photodiode-array) the lowest calibration limit is experimentally evaluated and compared with specific data for the detectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261474
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  • 4
    Electronic Resource
    Electronic Resource
    Sub-nanogram detection of dihydroartemisinin after chemical derivatization with diacetyldihydrofluorescein followed by high-performance liquid chromatography and UV absorption (1987)
    Springer
    Chromatographia 23 (1987), S. 112-114 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pre-column derivatization ; Ultraviolet detector sensitivity ; Dihydroartemisinin ; Diacetyldihydrofluorescein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use of diacetyldihydrofluorescein (DADF) for derivatization of dihydroartemisinin (dihydroqinghaosu, DHQHS) is proposed. The reaction between DHQHS and this reagent in the presence of 4-dimethylaminopyridine (DMAP) and N,N′-dicyclohexylcarbodiimide (DCC) was complete in 8 hours at room temperature giving about 80 per cent theoretical yield. The derivative showed intense UV absorption, thus providing a sensitivity of 0.1 nanogram by UV detection after column separation. The influences of the ratio of the reagents, reaction temperature, chromatographic conditions and the extent of detection linearity were investigated. The reaction gave consistent results and chromatographic separation was not affected by an excess of the reagent or side products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312884
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  • 5
    Electronic Resource
    Electronic Resource
    HPLC in photokinetics: Determination of reaction mechanism and photochemical quantum yields of (E)-1-phenylpropene (1987)
    Springer
    Chromatographia 23 (1987), S. 395-400 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Photokinetic data ; Reaction mechanism ; (E)-1-phenylpropene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A combined method of high-performance liquid chromatography and UV-absorption spectroscopy is described for use in dynamic systems. It provides a way of obtaining detailed mechanistic information as well as quantitative data (rate constants, quantum yields), even though neither mechanism nor photoproducts are known. The kinetic treatment of the photoreaction of (E)-1-phenylpropene was successful, showing a photo-isomerization and a parallel step. Information on this additional step is obtained by using HPLC to observe the changes in the concentrations of the reactants' selectivity. The necessity of process control is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311813
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of particulate fatty acids as P-bromophenacyl- or phenylphenacylesters using HPLC (1987)
    Springer
    Chromatographia 23 (1987), S. 419-422 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Fatty acid esters ; Particulate material in seawater
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method for the determination of fatty acids of the molecular weight range of propionic to erucic acid is reported. The acids are converted to either p-bromophenacyl-or p-phenylphenacylesters and the esters are separated by HPLC and detected by UV-absorption. Twentytwo esters, including saturated, monoolefinic and polyunsaturated ones were separated within one HPLC-run. The detection limit is about 5 pmol per fatty acid. The application of the method to particulate material is described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311817
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  • 7
    Electronic Resource
    Electronic Resource
    New polymer coated anion-exchange HPLC-phases: Immobilization of poly (2-hydroxy, 3N-ethylenediamino) butadiene on silica and alumina (1987)
    Springer
    Chromatographia 23 (1987), S. 435-441 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange stationary phases ; Polymer coating ; Cross-linking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary PHEB=POLY(2-hydroxy, 3N-ethylenediamino)butadiene has been synthesized. This unsaturated pre-polymer can be immobilized on different, preferably inorganic supports of suitable porosity such as silica or alumina by cross-linking. Weak anion-exchange phase are obtained. Such phases do not have the disadvantages of organic polymeric phases, regarding pressure stability and swelling by solvent influence. The ion-exchange capacity and the retentivity of IE-separations can deliberately be varied via the thickness of the cross-linked polymer layer. Alumina can also be coated with PHEB applying the same cross-linking procedure. Such phases exhibit an exceptional chemical stability even when operated with mobile phases at very high pH-values. Separations of excellent selectivity are achieved for inorganic anions, as well as with mixtures of aliphatic and aromatic free acids also including hydroxy- (mono- or poly)carboxylic acids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311821
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  • 8
    Electronic Resource
    Electronic Resource
    Application of the electrostatic interaction concept for the study of the retention behaviour of peropyrene-type polycyclic aromatic hydrocarbons in reversed-phase liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 473-476 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase systems ; Stationary phase-solute interactions ; Polycyclic aromatics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Capacity factors of peropyrene-type polycyclic aromatic hydrocarbons were measured using 15 different liquid chromatographic reversed phase systems. On the basis of the retention data the electric interaction indices have been calculated. Application of these indices for structure-retention studies on peropyrene-type polycyclic aromatic hydrocarbons is demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02309413
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  • 9
    Electronic Resource
    Electronic Resource
    Separation of gonadal steroid epimers using high performance liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 31-32 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gonadal steroids ; Epimers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chromatographic separation of biologically active epimeric steroids was carried out using a combination of normal and reversed phases. Testosterone (17β-OH) was separated from its 17α-OH epimer epitestosterone using a normal phase silica column whereas their reduced 5α-metabolites were separated on a reversed phase system. The separation of other gonadal steroids including the epimers 20α- and 20β-hydroxypregn-4-en-3-one is also discussed. The technique is particularly useful for separating mixtures of naturally occurring steroid epimers prior to radioimmunoassay.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02310414
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  • 10
    Electronic Resource
    Electronic Resource
    Separation of chlorophylls and their degradation products in marine phytoplankton by reversed-phase high-performance liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 26-30 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ammonium acetate buffer eluent ; Chlorophylls and degradation products ; Marine phytoplankton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An RP-HPLC procedure which separates chlorophylls and their degradation products is described. By employing an amonium acetate buffered mobile phase and a linear gradient elution, complex mixtures of chloroand phaeopigments are separated in less than 30 minutes. The method has been applied to the control of chlorophyll enzymatic degradation in cultures of two algal species, and has also been successfully used in the analysis of algal xanthophylls.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02310413
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  • 11
    Electronic Resource
    Electronic Resource
    Reversed-phase HPLC behaviour of metal complexes with 4-(2-pyridylazo) resorcinol. A detailed study in the light of solvophobic theory (1987)
    Springer
    Chromatographia 23 (1987), S. 736-746 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Behaviour of metal complexes ; Solvophobic theory
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The chromatographic behaviour of Cu(II), Fe(II), Ni(II) and Co(II) complexes with 4-(2-pyridylazo)resorcinol was studied. The experimental results were very sensitive even to less obvious operational parameters like the kind of the cation (sodium or ammonium) of the phosphate salt used as buffer. The puzzling pattern of the data obtained was interpreted in terms of the equations formulated by Horvath's ‘olvophobic” theory which correlates the capacity factors of the solutes with the surface tension of the mobile phase. A satisfactory rationalization of the data was obtained together with qualitative information on the stoichiometry and charge state of metal complexes. Useful suggestions about the direction to address the experimental work in order to obtain the best results was also obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312666
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  • 12
    Electronic Resource
    Electronic Resource
    Separation of transition metal ions and preconcentration of platinum (IV) and chromium (III) on alumina-immobilized diethylenetriaminepentaacetic acid by ligand exchange (1987)
    Springer
    Chromatographia 23 (1987), S. 747-751 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand Exchange ; Diethylenetriaminepentaacetic acid ; Transition metal ion separation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Basic alumina-bonded diethylenetriaminepentaacetic acid (DTPA) has been utilized for the separation and preconcentration of some transition metal ions on the basis of ligand exchange. Breakthrough capacity and rate of sorption have been studied. The distribution coefficients of 16 transition metal ions have been determined in demineralized water, 0.01 M sodium citrate and in four different pH systems. On the basis of differences in Kd values some quantitative separations of metal ions have been achieved. The greater selectivity behaviour (higher Kd values) of the adsorbent for Pt(IV)and Cr(III) has been utilized for their preconcentration in the presence of other metal ions. The method has been employed for the recovery of Pt(IV) and Cr(III) from tapwater and sea-water samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312667
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  • 13
    Electronic Resource
    Electronic Resource
    Gel filtration and high-performance liquid chromatographic analysis of phosphotungstic acid soluble peptides from blue cheeses (1987)
    Springer
    Chromatographia 23 (1987), S. 764-766 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gel permeation chromatography ; Cheese peptides ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The nitrogen fraction from cheese, soluble in phosphotungstic acid has been analyzed by gel permeation and high performance liquid chromatography. Elution profiles of this fraction on Sephadex G-10 show that there are no peptides of molecular weight higher than 700 daltons. Six fractions have been obtained. The first one has the peptides and some amino acids. Fractions II to VI contains mostly free amino acids. Fraction I has been separated into many peaks by HPLC. Six or seven of these peaks are presumed to correspond to peptides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312670
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  • 14
    Electronic Resource
    Electronic Resource
    Preparation and performances of small bore columns packed with reversed-phase materials and their use for the evaluation of air pollutants (1987)
    Springer
    Chromatographia 23 (1987), S. 803-810 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Small-bore packed columns ; Air pollutants ; PAH, nitro and oxy-PAH ; Aldehydes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of small bore columns (1 mm i.d.) packed with reversed-phase materials is described. High efficiency (Hmin=2 dp), coupled with a small C term (0.005 sec) have been obtained so that high speed can be combined with sufficient resolution for the separation of complex organic mixtures. These columns have been used for the separation of air pollutants dispersed in different matrices (air, particulate matter and rain water). Practical applications include the determination of aldehydes in air and emission samples, PAHs, nitrated and oxygenated PAHs in dust sampled from the stack of an industrial emission or collected in a urban area and the analysis of organic components dissolved in rain water collected at a rural site. Specific detection of these pollutants has been achieved by connecting small bore columns to UV absorbance, voltammetric and fluorimetric detectors. Mass spectra of some specific components have been recorded using the off-line technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311403
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  • 15
    Electronic Resource
    Electronic Resource
    HPLC determination of the aromatic fraction of gasoline (1987)
    Springer
    Chromatographia 23 (1987), S. 825-828 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gasoline ; Single-ring aromatic hydrocarbons ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This work reports a rapid and easy procedure for the analysis of the aromatic fraction in gasoline. No sample pretreatment is required, since the gasoline is diluted in methanol and directly injected into a liquid chromatograph. A spectrophotometer detector and a spectrofluorimeter detector are used in series. The procedure has been applied to a large number of Italian and European refined gasoline samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311407
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  • 16
    Electronic Resource
    Electronic Resource
    Separation of aldicarb, aldicarb sulfoxide, and aldicarb sulfone on unmodified silica with reverse-phase eluents (1987)
    Springer
    Chromatographia 23 (1987), S. 109-111 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Normal and reverse phase ; Aldicarb ; Aldicarb sulfoxide ; Aldicarb sulfone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Aldicarb, aldicarb sulfoxide, and aldicarb sulfone were chromatographed on an octyl-silica bonded-phase column and on an unmodified silica column using acetonitrile/water mobile phases. The elution order of the analytes from the silica column was different from that using the octyl-silica bonded phase and allowed confirmation of residues of aldicarb sulfoxide in citrus nectar. Isocratic elution of the unmodified silica column allowed rapid sample throughput.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312883
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  • 17
    Electronic Resource
    Electronic Resource
    High-performance ligand exchange chromatography on chiral diamine-bonded silica gel (1987)
    Springer
    Chromatographia 23 (1987), S. 118-120 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Ligand-exchange chromatography ; Chiral bonded phase ; Racemate resolution ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The resolution of racemates on chiral chemically bonded silica gel by high-performance ligand-exchange chromatography is described. The stationary phase was prepared by bonding (−) trans 1,2 cyclohexanediamine to silica gel through the coupling agent 3-glycidoxypropyl silane. The resolution of several α-amino acids and of compounds of pharmaceutical interest is reported.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312886
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  • 18
    Electronic Resource
    Electronic Resource
    Optimization of fat soluble vitamin separation in reversed-phase microcolumn liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 320-324 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore capillary columns ; Polymer based octadecylsilica bonded phase ; Fat soluble vitamins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Separation behavior of fat soluble vitamins on various chemically bonded materials in non-aqueous reversedphases microcolumn liquid chromatography has been investigated. The best performance was found on a polymer-based octadecyl bonded phase. Optimization of separation for vitamins D2, D3, E and E acetate has been tried using this polymer-based column and it has been found that a binary mobile phase consisting of acetonitrile and methanol gave complete separation of fat soluble vitamins.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02316175
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  • 19
    Electronic Resource
    Electronic Resource
    A comparative study of large volume injection techniques for microbore columns in HPLC (1987)
    Springer
    Chromatographia 23 (1987), S. 331-336 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Microbore columns ; Injection techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This paper focuses attention on the potentially larger signal-to-noise ratios produced by microbore columns in comparison with conventional columns. The increased chromatographic signals by the application of microbore columns are due to the lower chromatographic dilution of elution profiles which are proportional to the square of the column inner radius. Generally less than 1μl sample should be injected into microbore systems to obtain the full benefit of the column performance. However, since more sample can be loaded on conventional columns compared to microbore columns the advantage of improved signal-to-noise ratio can only be realised in situations where very little sample is available. To inject more than 1μl sample, at the same time avoiding extra band-broadening effects, suitable injection techniques must be available. In this study three injection methods for microbore systems that meet this condition, are studied and compared.
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    URL: http://dx.doi.org/10.1007/BF02316178
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  • 20
    Electronic Resource
    Electronic Resource
    High-performance liquid chromatography using a color-forming agent as a component of the mobile phase. Separation and determination of nickel and zinc wity xylenol orange (1987)
    Springer
    Chromatographia 23 (1987), S. 355-360 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Anion-exchange chromatography ; Xylenol orange ; Separation of nickel and zinc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid chromatographic procedure for separating nickel and zinc has been developed. Xylenol orange, which is one of the sensitive and commercially available color-forming agents, was used as a component of the mobile phase. The two ions could be separated on weak anion-exchange gels within 10 min. The procedure was suitable for the determination of nickel and zinc in relatively pure solutions with fairly high sensitivity. The described liquid chromatographic analysis would be also potentially applicable for any aqueous sample containing trace levels of metal cations at 1–10 ppm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02316182
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  • 21
    Electronic Resource
    Electronic Resource
    Determination of oligosaccharides (DP1-DP8) in samples with high content of salt and organic matter by reversed phase HPLC (1987)
    Springer
    Chromatographia 23 (1987), S. 557-560 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Oligosaccharides ; Interference by salts ; Complex biological samples ; Enzymatic assays
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A method is described for the determination of oligosaccharides in samples of high salt content by RP-HPLC with water as eluent and refractive index detection. The samples, mussel processing wastes which are used as media for microfungus and yeast cultures and hence for enzymatic assays (amilolitic capacity) of these microorganisms that develop within the wastes, have been treated with ethanol to precipitate the macromolecular organic matter and desalted by a modified mixed bed resin before chromatographic analysis is carried out.
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    URL: http://dx.doi.org/10.1007/BF02324863
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  • 22
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    Electronic Resource
    Group-type separation and determination of phenolic compounds in coal-derived products by HPLC (1987)
    Springer
    Chromatographia 23 (1987), S. 579-582 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Backflush technique ; Coal-derived procucts ; Separation of phenolic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid method was developed for the direct extraction of phenolic compounds from coal-derived products and subsequent isocratic HPLC analysis in a reversed-phase system by using the backflush technique.
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    URL: http://dx.doi.org/10.1007/BF02324868
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  • 23
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    Electronic Resource
    High-performance liquid chromatography using a color-forming agent as a mobile phase component. Separation of alkaline-earth-metal cations with arsenazo III and a non-porous gel column (1987)
    Springer
    Chromatographia 23 (1987), S. 583-589 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Non-porous gel ; Alkaline-earth cations ; Arsenazo III
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A liquid chromatographic procedure for separating alkaline-earth-metal cations with a non-porous gel column has been developed. Arsenazo III, which is one of the sensitive and commercially available color-forming agents, was used as a component of the mobile phase. Magnesium and calcium could be separated on the nonporous gel column within 55 seconds. The procedure was suitable for the separation of alkaline-earth-metal cations in relatively pure solutions with high sensitivity. Because of its rapidity the described procedure is also potentially applicable for any aqueous sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02324869
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  • 24
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    Electronic Resource
    High-performance liquid chromatography of biphenols and bis (hydroxyphenyl) propanes (dianes) with voltammetric and UV photometric detection (1987)
    Springer
    Chromatographia 23 (1987), S. 102-108 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Biphenols ; Dihydroxyphenylpropanes ; Voltammetric detection ; UV photometric detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The retention behaviour of mono- and dihydroxy derivatives of biphenol and bis(hydroxyphenyl)propanes was studied on chemically bonded C-18, CN-, phenyl, phenoxypropyl- and NH2 stationary phases and on silica gel. The effects of the mobile phase, i.e., of the methanol content, the ionic strength, pH and the contents of cationic and anionic ion-pairing agents on the retention data were investigated. In the reversed-phase systems, all the substances are satisfactorily separated except for 3- and 4-hydroxybiphenyl; these isomers can be separated on silica gel, using a mixture of heptane and propanol as the mobile phase. Sodium dodecylsulphate, present at concentrations higher than the critical micelle concentration (about 10−2 M, depending on the methanol content), causes a decrease in the retention times and an improvement in the separation. UV absorption spectra, calibration curves and the detection limit values were obtained at two wavelengths and at various salt concentrations in the mobile phase. Hydrodynamic voltammograms of the solutes were measured in a carbon fibre detector and the calibration curves and detection limit values were measured at the optimal voltage (+1.2 V/Ag/AgCl) as a function of the mobile phase composition. For most test substances voltammetric detection is two to three times more sensitive than UV detection. The combination of a UV and a voltammetric detector in series has been utilized to identify the products of microbial degradation of biphenyl.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02312882
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  • 25
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    Electronic Resource
    Reversed-phase ion-pair systems to predict partition coefficients of β-carbolines by HPLC and TLC (1987)
    Springer
    Chromatographia 23 (1987), S. 713-716 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thin-layer chromatography ; Ion pairing system ; Log P prediction ; Group contributions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A group of 17 β-carbolines was studied in HPLC and TLC systems in order to predict their partition coefficients (log P values). On account of the basic or acid character of some of these compounds, an ion pairing system gave the best results. Both HPLC and TLC data were comparable for log P prediction but severe pH conditions required the use of TLC plates. Retention data are quantitatively related to lipophilicity (expressed as the Hansch constant) and polarity (as the inductive constant) of the solute molecule.
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    Chitosan-coated silica gel as a new support in high-performance liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 731-735 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chitosan-coated silica gel ; Nucleotides ; Amino acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new stationary phase was prepared by immobilizing the chitosan, a natural hydrophilic polymer, on microparticolate silica gel. The effect of the polarity, pH and ionic strength of the mobile phase has been studied in order to find optimal conditions for the separation of nucleotides and aminoacids. The influence of the properties of the mobile phase on the retention was examined, allowing to employ the chitosan-coated silica gel both to anion exchange and adsorption, depending on the pH and the polarity of the eluent used.
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    Qualitative description of dispersive and inductive electrostatic interactions in reversed-phase liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 752-759 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase systems ; Phases-solute interactions ; Molecular polarizability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Variations in the electrostatic interaction have been studied using polycyclic aromatic hydrocarbons as standard compounds and different reversed-phase HPLC systems. Various methanol-water and acetonitrile-water binary mixtures were applied as the mobile phase. The stationary phases investigated consist of octadecylsilica and arenyl-silica. Using polarizability, dipole moment and ionization potential values of the solutes and mobile phase components as molecular descriptors an electrostatic interaction model is proposed.
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    Ligand exchange separation of amines on copper (II) sorbed on zinc silicate (1987)
    Springer
    Chromatographia 23 (1987), S. 93-96 
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    ISSN: 1612-1112
    Keywords: Paper chromatrography ; Column liquid chromatography ; Copper-impregnated zinc silicate ; Separation of amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Papers impregnated with Cu(II) sorbed on zinc silicate have been used to study the ligand exchange chromatographic behavior of amines. RF values of 16 amines have been studied in 6 different systems. On the basis of differences in RF values various analytically important qualitative separations of amines on impregnated papers and quantitative separations on columns of copper(II) sorbed on zinc silicate have been achieved.
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    Comparison of octadecyl-bonded silica and styrene-divinylbenzene copolymer sorbents for trace enrichment purposes fundamental aspects II. Linear chromatographic behaviour of the extracting supports (1987)
    Springer
    Chromatographia 23 (1987), S. 163-168 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Linear isotherms ; Octadecyl bonded silica ; Styrene divinylbenzene ; Frontal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Two reversed-phase LC systems were investigated by frontal analysis for the determination of linear chromatographic conditions, as defined according to the isotherm concept. The Partisil ODS-3 bonded silica and the PRP-1 polystyrene-divinylbenzene resin were used as stationary phases together withtrans-2-hexen-al as test solute and methanol-water mixtures as mobile phases. Particular attention was paid to the respective influence of the two main parameters which may cause sorbent overloading, that is, the capacity factor (k′) and the solute concentration in the mobile phase (Cm). Provided that k′Cm≤10−2 M, linear chromatographic behaviour was observed for both sorbents, the maximum capacities of which were found greater than 1mmolg−1.
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    Estimation of the band broadening contribution of HPLC equipment to column elution profiles (1987)
    Springer
    Chromatographia 23 (1987), S. 189-194 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Instrument bandbroadening by extrapolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Methods to determine the contribution of the chromatographic equipment to the total band broadening which involve replacing the column by a union or a capillary tube are not suitable as they involve a fundamental change in the chromatographic system. The linear extrapolation method, based on the estimation of the relative influence of the instrument variance on solutes with different capacity factors, is a more attractive alternative method since the column remains in the chromatographic system. This method is only valid when a number of conditions are satisfied. By meeting these conditions the error in the instrument variance by using the linear extrapolation method was determined. At the same time, ways to minimise these errors were studied. Use of the linear extrapolation method in combination with conventional columns of 4.6 mm i.d. appears to yield inaccurate results. In combination with microbore columns the method can be used, provided the columns have a maximum length of 5cm and contain a packing material with a particle size of 2 or 3μm. The error in the determined instrument variance is then of the order of 2μl2.
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    Non-aqueous reverse-phase HPLC analysis of triglycerides (1987)
    Springer
    Chromatographia 23 (1987), S. 209-214 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Review of triglyceride analysis ; Column temperature gradients ; Combined LC and other techniques
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The present review cites 54 papers dealing with reversephase HPLC analysis of triglycerides. The objective of the review was not merely to list the main contributions made in recent years but also to present a discussion of those papers representing qualitative advances and improvements helping to obviate the difficulties associated with this type of analysis. The use of mobile phase polarity and column temperature gradients and the combination of HPLC with other analytical methods such as mass spectrometry or GLC analysis of fatty acids are examples of such contributions.
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    Chromatographic packings made by solide phase synthesis (1987)
    Springer
    Chromatographia 23 (1987), S. 254-256 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Synthesis of stationary phases ; Influence of surface pH ; Influence of temperature, concentration and reaction ; time
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new way to produce liquid chromatographic stationary phases is suggested. The method is based upon a solide-phase reaction between the silica surface and the adsorbed silane molecules. The role of surface pH is demonstrated. The influence of other reaction conditions (concentration of the silane solution, effect of temperature and reaction time) is discussed.
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    Preparation of chiral stationary phase via activated carbamate intermediate for liquid chromatographic optical resolution (1987)
    Springer
    Chromatographia 23 (1987), S. 727-730 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chiral stationary phases ; Succinimido carbamate intermediates ; Amino acid enantiomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Chiral stationary phases (CSPs) for liquid chromatography were prepared by the way of an activated carbamate intermediate. The amino group of aminopropylsilyl silica gel was first activated by carbamylation with disuccinimido carbonate (DSC). The obtained activated carbamate silica gel (ACsil) proved useful as an intermediate for the preparation of urea-type CSPs. The reaction of ACsil with (S)- of (R)-1-(α-naphthyl)-ethylamine gave naphthylethylurea type CSPs. These CSPs were also obtained directly from aminopropylsilyl silica gel by its reaction with optically active (S)- or (R)-succinimido 1-(α-naphthyl)ethyl carbamate (SINEC). Several phenylthiohydantoin amino acid enantiomers and p-bromophenylcarbamyl amino acid enantiomers were resolved on the CSPs by elution with aqueous mobile phase.
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    Determination of the concentration of silanol groups by a chemical reaction with methyllithium and GC measurements of evolved methane (1987)
    Springer
    Chromatographia 23 (1987), S. 767-769 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography ; Bonded silica ; Residual silanol groups
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Silanol groups of chromatographic material surfaces were determined by chemical reaction with methyl-lithium. Evolved methane was measured by a gas chromatographic method using a column packed with molecular sieves. This chromatographic technique leads to very reproducible results, particularly for the control of the hydroxylation of a silica gel and for the analysis of residual groups at the surface of bonded silica.
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    Determination of low boiling aldehydes in air and exhaust gases by using annular denuders combined with HPLC techniques (1987)
    Springer
    Chromatographia 23 (1987), S. 829-834 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Aldehydes ; Annular denuder ; Environmental analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An improved procedure for the HPLC determination of C1−C3 aldehydes in environmental samples is described. These air pollutants are quantitatively collected on annular denuders coated with 2,4-Dinitrophenylhydrazine and analyzed as hydrazone derivatives by HPLC with UV absorbance and voltammetric detection. Collection efficiencies of aldehydes are reported and compared with other available methods. Practical examples of the application of the method are given.
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    Assay for urinary estriol during the menstrual cycle based on extraction by a graphitized carbon black cartridge followed by high-performance liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 835-838 
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    ISSN: 1612-1112
    Keywords: Estriol ; Urine ; Menstrual Cycle ; Column liquid chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high-performance liquid chromatography (HPLC) assay for estriol in nonpregnancy urine is described. After Enzymic hydrolysis, the estriol is extracted from urine by the sorbent trap technique utilizing graphitized carbon black (Carbopack B). After some washing steps, estriol is desorbed by a suitable solvent system. After solvent removal, the sample is injected into an HPLC column for estriol quantification. Analytical recovery of estriol was 96.1%. The precision of the method was 2.6 and 4.9% respectively at 145 and 10.6ng/ml of urine. The limit of sensitivity was set at 0.8 ng/ml of urine. The mean contents of estriol in the follicular and luteal phases were respectively 11.3 and 38.8 ng/ml of urine.
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    Influence of column temperature, water content, polarity, and acidity of isohydric solvents on the separation of butyrophenones on silica gel (1987)
    Springer
    Chromatographia 23 (1987), S. 893-898 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Isohydric solvents ; Butyrophenones ; Direct-silica gel
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The behaviour of butyrophenones in high performance liquid chromatography on silica gel using isohydric solvent systems has been studied. The influence of column temperature, water content, acidity and polarity of isohydric solvents on the retention, column efficiency and resolution of a series of butyrophenones have been investigated. Through the results obtained more insight has been gained into the theoretical aspects of the adsorption process on silica gel with isohydric solvent systems.
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    Large scale purification of synthesized oligodeoxyribonucleotides by reversed-phase chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 909-914 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase separation ; Oligodeoxyribonucleotides ; Isolation of pure material
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A reversed-phase chromatographic column suitable for the purification of chemically synthesized large oligodeoxyribonucleotides (oligo-DNA) was prepared. The specifications of this column are; the selected silica (Toyo Soda silica) with large pore size (at least 150 Å) and small particle diameter (5 μm desired) should be grafted only with monochloro alkylating reagent of long alkyl chain (sufficiently C18) so that the carbon content of the resultant packing material is 15–16%. Using this column, we could isolate the targeted large oligo-DNA (up to 50mer) in a large scale (75 μg per one cycle) from the impurities in the reaction mixture formed during the automated synthesis by the phosphite method.
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    A critical review of some liquid chromatography systems for the separation of sugars (1987)
    Springer
    Chromatographia 23 (1987), S. 292-300 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Separation of sugars ; Review
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary This contribution to the problems of carbohydrate (sugar) column liquid chromatography, evaluates several currently used systems (reversed phase octadecylated silica gel, amino modified silica gel, cation exchangers on polystyrene and on silica gel basis, polyol derivatised silica gel and anion exchange systems). The elution pattern, analysis time, column efficiency and column life time expectancy are considered to be the important points for this comparison. The application of silica gel-based cation exchanger and of polyol derivatised silica gel is new to this field. The comparison and/or evaluation tries to be critical and to come to a conclusion for the choice of a recommended system.
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    Liquid chromatographic determination of dimethadione and trimethadione in human serum on octadecyl treated microporous glass columns (1987)
    Springer
    Chromatographia 23 (1987), S. 325-327 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Packings of octadecylated microporous glass ; Dimethadione and trimethadione in serum ; Pancreatic stones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The liquid chromatographic determination of trimethadione (TMO) and its methabolite, dimethadione (DMO) were studied by high-performance liquid chromatography (HPLC) on octadecyl-modified microporous glasses, prepared with toluene solution containing octadecyl-dimethylchlorosilane, using two types of microporous glass with various mean pore diameters and/or specific surface areas. Using acetonitrile-water mixtures as eluents, TMO and DMO in human serum were separated on the glasses studied, but with different degrees of resolution. In this present study, we report the development of a rapid and selective HPLC method for the simultaneous analysis of TMO and DMO in human serum.
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    Characterization of some commercial poly (styrene-divinylbenzene) copolymers for reversed-phase HPLC1 (1987)
    Springer
    Chromatographia 23 (1987), S. 341-349 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cross-linked polystyrene ; Characterization of surfaces
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The properties of the poly(styrene-divinylbenzene) copolymers PRP-1 and PLRP-S have been studied by infrared spectroscopy and chromatographic techniques. The following results were obtained: PRP-1 and PLRP-S are spectroscopically very similar. Their surfaces are chemically neither homogeneous nor stable during use. Retained nonpolar solutes should be eluted with a mobile phase containing tetrahydrofuran. Uncharged acids and anions can be chromatographed without difficulty. Cations of amines should be chromatographed only with a mobile phase of low pH. Uncharged amino-alcohols cannot be chromatographed without the addition of a competitor.
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    Preparation of silanized silica with high ligand density. The effect of silane structure (1987)
    Springer
    Chromatographia 23 (1987), S. 442-446 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chemically bonded phases ; Kinetics of silanization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A wide-pore silica for HPLC with a particle size of 7.5 μm, specific surface area of 360m2/g, pore diameter of 20 nm and pore volume of 2.1 cm3/g was silanized with n-octadecyldimethyl-chlorosilane (ODMCS), n-octadecyldimethylmetoxysilane (ODMMS) and n-octadecyldimethyl-dimethylaminosilane (ODMAS), in sealed glass ampoules. The ligand density obtained with an excess of ODMCS and ODMMS was found to be limited by reaction equilibrium; at low (〈50%) conversion of the surface silanols, the reaction displays pseudo-first-order kinetics. Silanization with ODMAS, which seems to be sterically controlled at higher conversions, yields a relatively high concentration of bonded octadecyl ligands (4.24μmol/m2).
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    HPLC on pentalfuoroanilinopropyl silica gel (1987)
    Springer
    Chromatographia 23 (1987), S. 684-685 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Pentafluoroanilinopropyl silica gel ; Donor-acceptor complexes ; Aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The preparation of a new pentafluoroanilino-phase for HPLC is described. The retention times (tr) of about twenty aromatic hydrocarbons have been determinated. It has been shown that the aromatics were eluted according to the number of rings. The influence of water content in the mobile phase is commented.
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    HPLC determination of thiol drugs in pharmaceutical formulations using ethacrynic acid as a precolumn ultraviolet derivatization reagent (1987)
    Springer
    Chromatographia 23 (1987), S. 680-683 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiol drug analysis ; Derivatization by ethacrynic acid ; Pharmaceutical formulations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A high performance liquid chromatographic method has been developed for the determination of aliphatic thiol drugs, such as N-acetyl-L-cysteine, captopril and mercaptopropionylglycine in pharmaceutical formulations. The procedure involves a precolumn derivatization of the thiol drug with ethacrynic acid followed by reversedphase HPLC separation and UV detection. The conditions for a rapid and selective reaction of the thiols with ethacrynic acid have been investigated. The method proved to be suitable for a reliable and selective quality control of commercial dosage forms of the examined thiol drugs.
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    Trace analysis of sugars by HPLC and post-column derivatization (1987)
    Springer
    Chromatographia 23 (1987), S. 657-662 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Post-column derivatization ; Sugar analysis ; Wine characterization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A HPLC system with post-column derivatization for the quantitative analysis of sugars in complex matrices is described. As reagent a 0.2% solution of thymol in concentrated sulfuric acid has been used. The reaction is sensitive with reducing as well as non reducing sugars whereas sugar alcohols are discriminated. With this reagent and separation of sugars at high pH values with an anion exchange column it is possible to detect sugars in the ng range. Hence, it is possible to characterize wines not only by their fructose and glucose content but also by differences in the distribution of the other not fermentable sugars like trehalose, arabinose, galacturonic and glucuronic acid.
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    On-column catalysis of hydratization equilibria during liquid chromatographic analysis of acetaldehyde and formaldehyde (1987)
    Springer
    Chromatographia 23 (1987), S. 709-712 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Polymer-based support ; Aldehydes ; Fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The aldehydes were separated by reversed phase chromatography on a polymer-based support. Acid catalysis on the column was needed to obtain sufficiently fast equilibrium between acetaldehyde and its hydrate. Deuterium labeled acetaldehyde (D3) yielded complete separation from the nonlabeled compound, probably due to a difference in hydratization. Fluorescent products were obtained by reaction between the aldehydes and a mixture of ammonia and dimedone (5.5-dimethyl-1.3-cyclohexanedione). The fluorescence was detected at 460 nm after excitation at 390 nm. A reaction time of 42 seconds at 90°C in a knitted teflon capillary produced detection limits of 0.5 and 1 ng for acetaldehyde and formeldehyde, respectively. A method for preparation of a stable reagent with low background fluorescence is described.
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    Effects of reducing agents on the determination of thiolic compounds in the presence of their disulfides using bimane pre-column derivatization (1987)
    Springer
    Chromatographia 23 (1987), S. 717-721 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Thiols and disulfides ; Fluorescence derivatization ; Monobromobimane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The influence of reducing agents (sodium borohydride, tributylphosphine, dithioerythritol and dithiothreitol) on the conversion of disulfides into their parent thiols, with specific application to cysteine was investigated. Dithioerythritol and dithiothreitol were found to be most suitable for this reaction. A contact time of one hour at room temperature provided quantitative reduction as tested using cystine as a pure disulfide standard. A modified fluorescence labelling procedure with monobromobimane followed by reversed-phase HPLC allows quantitation of the parent thiol and the disulfide content when completing the labelling reaction with and without preliminary treatment with reducing agent. The effects of various bimane reducing agent ratios on the yield of the reaction are discussed. Precautions should be taken when dealing with complex matrices with respect to reagent concentrations and ratios.
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    Activated carbamate reagent as chiral derivatizing agent for liquid chromatographic optical resolution of enantiomeric amino compounds (1987)
    Springer
    Chromatographia 23 (1987), S. 899-902 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Chrial separations ; Succinimido carbamate derivatives ; Propranolol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A chiral derivatization reagent having activated succinimido carbamate moieties were developed for the optical resolution of enantiomeric amines by high-performance liquid chromatography. Succinimido R-(+)- or S-(−)-1-phenylethyl and R-(+)- or S-(−)-1-(α-naphthyl)-ethyl carbamates were synthesized by the reaction of optically active phenylethyl and naphthylethyl amines with discuccinimido carbonate (DSC). These reagents reacted with both primary and secondary amine enantiomers such as amino acids and β-amino alcohols to give the corresponding diastereomeric urea derivatives. These diastereomers were efficiently separated by reversed-phase liquid chromatography and detected by their absorption or the fluorescence of the chromophores. The chiral derivatization procedure was applied to the separation and determination of enantiomeric propranolol in serum.
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    Optimization of the separation of polymethoxylated flavones in reversed phase liquid chromatography (1987)
    Springer
    Chromatographia 23 (1987), S. 15-20 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed phase operation ; Calculation of optimum solvent composition ; Polymethoxylated flavones
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An optimization procedure for the chromatographic separation of polymethoxylated flavones is described. A polyhedron working volume is drawn from a truncated tetrahedron constructed from the four solvents selected. The response function is an n'th degree polynomial the coefficients of which are calculated through the least squares method by means of B=(X′X)−1X′Y in which X′X is the information matrix (X′X)−1 the variance covariance matrix. X is the matrix of the model (polynomial built from the selected experiments) and X′ the transposed matrix. Y is the quality of the chromatogram defined by the resolution of each pair of solutes. An exchange algorithm matrix yields the minimum number of runs necessary to obtain a correct B. Isoresponses curves are drawn by intersection of a cubic volume which includes the polyhedron to give a better insight. An optimal zone is then determined and provides the solvent composition. An optimized chromatogram of 8 methoxylated flavones demonstrates the application of the method.
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    Chromatographic determination of lactulose (1987)
    Springer
    Chromatographia 23 (1987), S. 132-136 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Column liquid chromatography ; Thin-layer chromatography ; Analysis of lactulose in carbohydrate mixtures
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Lactulose is a disaccharide with important implications in medicine, nutrition and dairy technology. It has to be determined usually as a minor component in complex matrices containing many other sugars. This paper describes the different chromatographic techniques (planar, liquid and gas chromatography) which have been proposed for the separation and quantification of lactulose in mixtures with other carbohydrates; the advantages of each technique are compared and some features where more research is necessary are outlined.
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    URL: http://dx.doi.org/10.1007/BF02312889
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    A study of the liquid chromatography of some fungicidally active arylsulphonohydrazides (1987)
    Springer
    Chromatographia 23 (1987), S. 328-330 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Arylsulphonohydrazides ; On-column hydrolysis ; Fungicides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A number of fungicidally active arylsulphonohydrazides are examined by normal- and reversed-phase liquid chromatography. Although good separations are achieved by reversed-phase LC, difficulties are encountered due to analyte hydrolysis. On the other hand, satisfactory analyses are possible by normal-phase LC particularly on modified silicas.
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    URL: http://dx.doi.org/10.1007/BF02316177
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    Rapid extraction of codeine and morphine in whole blood for HPLC analysis (1987)
    Springer
    Chromatographia 23 (1987), S. 377-378 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Solid phase extraction ; Codeine and morphine in blood
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A rapid and efficient procedure is described for the extraction and analysis of codeine and morphine in whole blood. Red blood cells were fragmented by sonication and the blood sample extracted by passing through a bonded silica column (Bond Elute®). The adsorbed drugs were washed and eluted followed by analysis by HPLC. Recoveries were between 95–100% at 5 ng/ml concentrations.
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    Liquid chromatographic analysis with electrochemical detection for metoclopramide in human plasma (1987)
    Springer
    Chromatographia 23 (1987), S. 651-652 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Metoclopramide ; Electrochemical detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A simple, reproducible liquid-chromatographic method for determination of metoclopramide anti-emetic and anti-spasmodic agent is described. Metoclopramide is extracted from alkalinized plasma into diethylether, then separated with a sperisorb CN column and measured through amperometric detection at +1,4 volt vs Ag/ AgCl. The average extraction recovery was 92%. Standard curves were linear and reproducible from 0.05 to 1.5 mg/ L. Within-day CV was better than 6%.
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    A solvent-free sampling method for airborne toluene diisocyanate (1987)
    Springer
    Chromatographia 23 (1987), S. 507-511 
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    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Toluene Diisocyanate in air ; Collector for air sampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A useful method of sampling and measurement of toluene diisocyanate concentration in atmosphere is described. The sampler consists of glass-fibre filters impregnated with the reagent 1-(2-methoxyphenyl)piperazine1 so that the 2,4 and 2,6 isomers of TDI react to form urea derivatives which are analysed by high performance liquid chromatography in isocratic mode on cyan-amino and C18 bonded phases. A dynamic system was used to generate standard atmospheres of TDI and to validate the sampling method within the humidity range of 0% to 75%. A coated filter, a bubbling solution and an impregnated silica gel were compared as samplers requiring the piperazine reagent in performance experiments.
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    Pattern recognition for earthquake detection by mental pictures (1987)
    Springer
    In:  Bull., Polar Proj. OP-O3A4, ASST'87, Berlin, Springer, vol. 81A, no. 16, pp. 347-350, (ISBN: 3-540-23712-7)
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    Publication Date: 1987
    Keywords: Detectors ; Seismology ; Pattern recognition
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    Automatische Detektion und Auswertung in Seismischen Netzen (1987)
    DGG
    In:  47. DGG-Tagung, Clausthal, DGG, vol. C 560, 183 pp., no. GL-TR-89-0143, pp. 235, (ISBN 3-933346-037)
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    Publication Date: 1987
    Keywords: Data analysis / ~ processing ; Detectors ; ARR ; arc ; BUG ; Seismology ; Pattern recognition ; Seismic networks
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    Determination of urinary 5-S-cysteinyldopamine by high-performance liquid chromatography with electrochemical detection (1986)
    Springer
    Chromatographia 21 (1986), S. 645-647 
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    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.
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    Optimization of a reaction detector for analysis at the femtomol level of carbamate insecticides by HPLC (1986)
    Springer
    Chromatographia 21 (1986), S. 136-142 
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    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.
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    Optimization of enantiomeric separations with chiral bonded phases (1986)
    Springer
    Chromatographia 21 (1986), S. 205-213 
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    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.
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    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 
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    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.
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    Determination of pyridate and its main metabolite CL-9673 in plant materials (1986)
    Springer
    Chromatographia 22 (1986), S. 40-42 
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    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.
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    Liquid chromatographic capacity factor as an indicator of lipophilicity in a series of betablocker drugs (1986)
    Springer
    Chromatographia 22 (1986), S. 48-50 
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    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.
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    A limit to alternate column recycle chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 81-87 
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    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.
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    Specific retention behaviour of metal (III) tetraphenylporphyrins in non-aqueous, reversed high-performance liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 43-47 
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    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.
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    Factors affecting adsorption of organic solutes on cellulose acetate in an aqueous solution system (1986)
    Springer
    Chromatographia 22 (1986), S. 55-58 
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    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―.
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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 
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    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.
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    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 
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    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.
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    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 
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    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.
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    Analysis of flavonol aglycones in wine extracts by high performance liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 157-159 
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    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.
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    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 
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    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.
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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 
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    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.
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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 
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    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.
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    Crocheted PTFE reactors for post-column photochemistry in HPLC (1986)
    Springer
    Chromatographia 22 (1986), S. 231-234 
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    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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    Diffusion inside particles in HPLC columns (1986)
    Springer
    Chromatographia 22 (1986), S. 319-328 
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    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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    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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    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.
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    URL: http://dx.doi.org/10.1007/BF02310587
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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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    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 
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    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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    High-performance liquid chromatographic determination of glaucine inGlaucium flavum crantz (1986)
    Springer
    Chromatographia 21 (1986), S. 227-228 
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    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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    On the chromatography mechanism of reversed-phase liquid chromatography (1986)
    Springer
    Chromatographia 21 (1986), S. 229-233 
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    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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    Matrix effect on the retention in reversed-phase liquid chromatography (1986)
    Springer
    Chromatographia 22 (1986), S. 194-198 
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    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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    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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    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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    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 
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    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257302
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  • 98
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02257314
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  • 99
    Electronic Resource
    Electronic Resource
    Poly(vinylpyrrolidone)-coated silica: A versatile, polar stationary phase for HPLC (1986)
    Springer
    Chromatographia 21 (1986), S. 573-582 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311839
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  • 100
    Electronic Resource
    Electronic Resource
    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 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02310595
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