摘要:

In this paper the influence of NaCl concentration in the binding buffer on the analysis of lysozyme in chicken egg white using MonoQ® anion exchange column is examined. When using a mobile phase having pH 9.5, lysozyme (being positively charged at that pH) is not expected to bind to the anion exchange column. However, when the NaCl concentration in the binding buffer is lower than 70 mM, lysozyme is found to bind to the column, probably due to non-specific adsorption. This results in lysozyme splitting into two peaks; a primary peak in the column void volume, and a secondary lysozyme peak in the NaCl salt gradient. The proportion of lysozyme in the secondary peak decreases with an increase in NaCl concentration in the binding buffer. No secondary peaks are observed when the NaCl concentration in binding buffer is greater than 70 mM. This observation is confirmed by experiments carried out with pure lysozyme.

ISSN:1082-6076    

DOI:10.1081/JLC-100100439

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The binding of ADP to chloroplast ATPase (CF1) has been studied by chromatographic methods (Hummel and Dreyer method and chromatographic determination of the enzymatic inhibition).

ISSN:1082-6076    

DOI:10.1081/JLC-100100440

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The binding of ADP to chloroplast ATPase (CF1) has been measured by the chromatographic method of Hummel and Dreyer which allows low affinity binding determinations. Besides about 1.5 endogenous ADP molecules that are irreversibly bound to CF1or slowly exchangeable in the experimental conditions, ADP binds to CF1in the presence of Mg2+with an apparent unique dissociation constant of 64 μM, up to a total of 6 ± 0.5 moles/mole, when Mg2+is in excess over ADP. Under these conditions, the major part of the bound nucleotide is in the metal complexed form. Metal free ADP also binds to CF1, with a dissociation constant of 5 to 15 μM, measured by competitive inhibition of ATPase activity, at low Mg2+concentration.

ISSN:1082-6076    

DOI:10.1081/JLC-100100441

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A γ-cyclodextrin (γ-CD) modified micellar electrokinetic capillary chromatographic (CD-MEKC) method has been developed to separate PAH metabolites. Baseline resolution of six acidic PAH metabolites was achieved within 14 min. The effects of several separation parameters were investigated in detail. These were the γ-CD concentration, sodium dodecyl sulfate (SDS) concentration, pH of the buffer, organic modifier, and urea concentration. The apparent capacity factors (k′app) increased linearly with SDS concentration which was consistent with theory. Possible mechanisms that account for the differences in the apparent distribution coefficients (Kapp) were proposed. The CD-MEKC method was compared with a capillary zone electrophoresis (CZE) method that we developed previously for the separation of the PAH metabolites.

ISSN:1082-6076    

DOI:10.1081/JLC-100100442

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

As a potential anticancer agent, the isoflavones contained in soybeans were considered for separation by reversed-phase high performance liquid chromatography (RP-HPLC). The mobile phases were the ternary system of water/acetonitrile/acetic acid. In this work, the four different columns of μ-Bondapak (0.39 × 30 cm, 10 μm), and the other three empty stainless steel columns (0.39 × 30, 1 × 25, 1″ × 25 cm) packed with 15 μm C18packings were used. The experimental variables were the gradient conditions and mobile phase composition. The increased number of gradient steps enabled the separation of isoflavones in the larger columns. The separation condition of 1″ × 25 cm column was determined by experiments of the systematic sequence of the smaller columns. For the largest column, 2 mL of sample was separated with the three gradient steps at 18 mL/min of mobile phase flow rate. The isoflavones of daidzein, glycitin, genistin, daidzin, and glycitein were identified by LC-MS with the purified components.

ISSN:1082-6076    

DOI:10.1081/JLC-100100443

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Centrifugal partition chromatography linked with evaporative light scattering detection has been investigated to achieve the large scale-up isolation of oraposide which is a phenylpropanoid glycoside having a radical-scavenging activity. A two-phase solvent system has been studied to improve the yield of pure product and to decrease the cost of purification. A comparison with preparative HPLC has been made.

ISSN:1082-6076    

DOI:10.1081/JLC-100100444

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A micellar electrokinetic capillary chromatography (MECC) method suitable for the determination of antioxidants and preservatives permitted in cosmetic products is described. Unlike reversed phase high performance liquid chromatography (HPLC) this method simultaneously separates ionic solutes (sorbic acid and benzoic acid) and non-polar components (butylated hydroxytoluene and dodecyl gallate). A buffer consisting of 15 mM sodium dodecyl sulfate, 35 mM sodium cholate, 10 mM boric acid, and 10 mM sodium tetraborate adjusted to pH 9.5 and an 80 cm (total length) bare fused silica column gave good separations. The determination of additives in some cosmetic products was performed using both MECC and HPLC. There was good agreement between the methods.

ISSN:1082-6076    

DOI:10.1081/JLC-100100445

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A sensitive and simple high performance liquid chromatographic method for the assay of fluoxetine HCl was developed. The procedure is based on the use of the reversed-phase high performance liquid chromatographic method with UV detector. Each analysis required no longer than 6 minutes. The detector response was linear in the range of 0.01–50 μg/mL for fluoxetine HCl. The detection limit was found to be 0.0057 μg/mL. There was no significant difference between interday and intraday studies for fluoxetine HCl determined for two different concentrations. This method was applied, without any interferences from the excipients, for the determination of the drug in capsules and in drug dissolution studies. This method can be useful in routine quality control analysis of fluoxetine HCl pharmaceutical dosage form.

ISSN:1082-6076    

DOI:10.1081/JLC-100100446

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This study aimed to develop a simple, sensitive, and accurate HPLC method for the simultaneous determination of verapamil and norverapamil enantiomers in human plasma. An internal standard (diphenhydramine) was used and separations of verapamil and norverapamil enantiomers were done at room temperature. Chromatographic separation was achieved using a Chiralcel®OD-RH column (5 μm, 4.6 mm i.d. × 15 cm, Daicel Chemical Industries Ltd., Tokyo, Japan) and a mobile phase consisting of 30 mM hexafluorophosphate and acetonitrile (66 : 34, v/v, pH 4.6). Detection of S- and R-verapamil and the metabolites, S- and R-norverapamil was accomplished with a fluorescence detector. The wavelengths of excitation and emission were set at 280 nm and 315 nm respectively.

ISSN:1082-6076    

DOI:10.1081/JLC-100100447

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A reversed-phase high performance liquid chromatographic (HPLC) method for the determination of the activated cyclophosphamide (CP) metabolite 4-hydroxycyclophosphamide (4-OHCP) in human plasma and red blood cells is described. 4-OHCP is very unstable in biological matrices. Therefore, it was treated, immediately after sampling, with semicarbazide to form a stable semicarbazone derivative, which was identified with electron spray mass spectrometry. The derivative was analysed with HPLC with ultraviolet (UV) detection at 230 nm. Sample pre-treatment consisted of a liquid-liquid extraction with ethyl acetate, the chromatography system was a 25 cm C8 column (particle size 5 μm) with a mobile phase of acetonitrile-0.025 M potassium phosphate buffer (15:85 v/v) pH 6.0. After assay optimisation, the method was validated and stability studies were carried out. The method proved linear in clinically relevant concentrations (50-5000 ng/mL). The lower limit of quantitation was 50 ng/mL. Accuracy and precision were below 7% over the full concentration range. A calibration curve in plasma can also be used for the quantification of 4-OHCP in red blood cells. The derivative was found to be stable for at least 11 months when stored at −70 °C. A pharmacokinetic pilot study in a patient treated with 1000 mg/m2CP in combination with thioTEPA and carboplatin demonstrated the applicability of the assay for the determination of 4-OHCP in plasma and red blood cells.

ISSN:1082-6076    

DOI:10.1081/JLC-100100448

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor