摘要:

Silica beads of 6μm average diameter were silanized with methylvinyldiethoxysilane and then coated with phenyl-vinylmethylpolysiloxane. The chromatography (RP-HPLC) with the prepared material has superior ability for the separation of polar, non-polar and basic compounds. The chromatographic peaks are symmetric. Its stability has been studied. After continuous use for four months, the carbon content and chromatographic behavior of the phase were unchanged.

ISSN:1082-6076    

DOI:10.1080/10826079808001245

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The retention behavior of nine proteins was experimentally detected by using high performance size exclusion chromatography (SEC). At low ionic strength of mobile phase, the retention behavior of proteins is dependent of not only size exclusion but also electrostatic interaction. At the same pH value of mobile phase as the isoelectric point of a protein, the protein molecule is neutral. When the pH value of mobile phase is higher than the isoelectric point of a protein, the protein molecule carries a negative charge, resulting in size exclusion and ionic exclusion occuring together. Otherwise, ionic adsorption dominates in electrostatic interaction. At middle ionic strength of mobile phase, the retention behavior is governed by size exclusion mechanism. The experimental result indicated that in order to achieve ideal size exclusion the elution conditions for proteins should be ionic strength 0.1∼0.3 M and pH value near its isoelectric point. A linear “calibration curve” was correlated by eight proteins except hemoglobin, in which the related coefficient was as high as 0.9977.

ISSN:1082-6076    

DOI:10.1080/10826079808001246

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Two means for chemical modification of amine groups are investigated as to their compatibility with capillary electrophoresis (CE) and fluorescent derivatization of polypeptides. The chemical modification reagents, which are currently under examination for protein modification and subsequent peptide mapping, are selected such that there is minimal impact (permanent modification of amine groups with little or no effect on pKa, relative size, solubility, etc.) or no impact (clean removal of the reagent after fluorescent derivatization) on the subsequent electrophoretic behavior of the fluorescently labeled peptide. Capillary electrophoresis conditions that permit the separation of the three possible amine modification products of the model peptide studied, performic acid oxidized insulin B-chain (two primary amine groups), are demonstrated. The distribution of formed products can thus be probed by CE.

ISSN:1082-6076    

DOI:10.1080/10826079808001247

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Based on previous work using the uni-variate approach to optimize the separation of nine Lauraceous aporphine alkaloids, lindcarpine, laurolitsine,N-methyllindcarpine, boldine, norpredicentrine, isocorydine, laurotetanine,N-methyl-laurotetanine, and isoboldine, by micellar electrokinetic chromatography, a three-parameter overlapping resolution mapping (ORM) scheme was employed to optimize the separation of these compounds. With the other conditions preoptimized, three buffer parameters, i.e., the concentrations of sodium borate, sodium dodecylsulfate, and sodium heptanesulfonate were chosen to carry out the optimization process. Conditions were identified that allowed base-line separation of the nine aporphines and the internal standard within eight minutes. These results show that ORM is an efficient optimization procedure, although some primary separation data is first required.

ISSN:1082-6076    

DOI:10.1080/10826079808001248

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

High performance liquid chromatography (HPLC) was applied to study the behavior of a series of 1-hydroxy-imidazole-3-N-oxides (HIO) in solution. Some thermodynamic parameters influencing solute retention were determined from the temperature dependence of the capacity factor (k). A linear relation was derived between k and molecular parameters considering intermolecular association, which was predicted and confirmed. ΔGadsvalues are also highly correlated with connectivity index, molar refractivity and Van der Waals volumes. Retention data for twenty closely related imidazoles were measured and analyzed in relation to hydrophilic parameters.

ISSN:1082-6076    

DOI:10.1080/10826079808001249

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The reversed-phase chromatographic behavior of the powerful new anti-migraine drug rizatriptan benzoate and its potential impurities has been studied. Molecular dynamics calculations were used to explain the elution order of the two regioisomers of rizatriptan formed during its synthesis in terms of conformational differences. Further, van't Hoff plots for a mixture of the two regiosiomers and one potential process impurity were non-linear (R = 0.937 - 0.965) when chromatographed on an SB-Phenyl column. However, van't Hoff plots for the same analytes were linear (R ≥ 0.996) when chromatographed on an C8column. The break in the van't Hoff plots generated with an SB-Phenyl phase occurs at ambient temperature (∼25°C) and is attributed to changes in stationary phase morphology as a function of temperature.

ISSN:1082-6076    

DOI:10.1080/10826079808001250

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A rapid, accurate, and sensitive method has been developed for the quantitative determination of hydrochlorothiazide (HCT), an antihypertensive-diuretic agent. A Nucleosil C18100×4.6 mm, 5 μm analytical column was used with a mixture of CH3CN-1% acetic acid, at a volume ratio 20:80. Detection was performed with a variable wavelength UV-visible detector at 270 nm, resulting in detection limits of 0.2 ng per 20 μL injection.

ISSN:1082-6076    

DOI:10.1080/10826079808001251

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Reversed-phase HPLC is usually the method of choice for compounds that dissolve in water/organic mixtures, even for samples that contain ionizable compounds. However, reversed-phase ion-pair chromatography (RP-IPC) is often a useful alternative for such samples, particularly if the components are highly basic or acidic. With this technique an aqueous/organic mobile phase is used along with a buffer and an ion-pairing reagent to provide more retention and higher selectivity than are afforded by the column and organic solvents alone. The retention effects of ammonium acetate, sodium acetate, potassium phosphate, and triethylamine (TEA) on a pharmaceutical compound (SK&F 108566) and its stereoisomer (SB 206328) were studied. Evidence indicated that SK&F 108566 and SB 206328 exhibited ion-pair formation with simple buffer systems and the ion-pair occurred in the mobile phase prior to the complex binding rapidly to the stationary phase.

ISSN:1082-6076    

DOI:10.1080/10826079808001252

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A sensitive high performance liquid chromatographic (HPLC) assay was developed to quantitate the organic amine proton-acceptor, tris(hydroxymethyl)aminomethane (THAM) in human plasma, erythrocytes, and whole blood. An aliquot of the sample was heat evaporated (200°C for 2 h), derivatized, extracted, and then injected onto a symmetry C8column. The UV absorbance of the effluent was monitored at 237 nm. 2-Amino-2-methyl-1,3-propanediol was found to be an appropriate internal standard. The method has been applied to quantitate the samples from patients undergoing orthotopic liver transplantation. The assay has also been employed to assess thein vitrotime of THAM-uptake into the erythrocytes from blood samples incubated at 37°C.

ISSN:1082-6076    

DOI:10.1080/10826079808001253

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

High performance anion exchange chromatography with conductivity detection (HPAEC-CD) was used to separate and assay 2-mono-, 2-di-, and 2-triphosphate esters of L-ascorbic acid and four inorganic phosphates. The separation was performed on a Dionex AS-11 analytical column with a linear gradient of 20 mM to 80 mM aqueous sodium hydroxide in 10 min. The sensitivities (detection limits) were about 0.1–0.15 μg/mL (2–3 ng) for the inorganic phosphates and 0.2 μg/mL (4 ng) for each 2-phosphate ester of L-ascorbic acid, all calculated as free-acid forms. The method was applied to determine the major components in a commercial phosphorylated L-ascorbate.

ISSN:1082-6076    

DOI:10.1080/10826079808001254

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor