摘要:

A method involving high performance liquid chromatography with tandem mass spectrometric detection was developed to determine the concentration of a new macrolide derivative, ABT-229, in human plasma. The analyte was extracted using liquid-liquid extraction with a mixture of ethyl acetate and hexane at basic pH. Detection was highly specific for the analyte of interest, as evidenced by the lack of interference in the chromatograms of drug-free plasma extracts. The lower limit of quantitation was 0.10 ng/mL based on 1 mL of extracted plasma. The linear calibration range of the procedure extended from 0.10 to 199 ng/mL. The method proved reliable and rugged; within-run and day-to-day relative standard deviations were less than 10%. The stability of ABT-229 under frozen storage, room temperature, and freeze/thaw conditions was found to be excellent. Plasma concentrations determined by the method were highly comparable with data obtained by electrochemical detection.

ISSN:1082-6076    

DOI:10.1081/JLC-100101687

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The separation selectivity of inorganic anions in capillary zone electrophoresis with reversed electroosmotic flow was altered by incorporating ≤7.5% v/v butan-1-ol in a chromate-based background electrolyte (BGE). Pronounced selectivity changes occurred for lipophilic anions, whereas, for the common inorganic anions, the changes were minor. The likely causes for these selectivity changes are discussed. Furthermore, BGEs with butan-1-ol yielded separations with (i) short times for lipophilic anions, (ii) smoother baselines, (iii) better resolutions, (iv) increased peak heights for iodide and thiocyanate, and (v) good reproducibility (≤4% RSD, n = 11) for absolute migration time, peak area, and peak height.

ISSN:1082-6076    

DOI:10.1081/JLC-100101688

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Capillary zone electrophoresis (CZE) was used to determine the pKavalues of six environmentally and metabolically important PAH metabolites. The pKavalues obtained from CZE were close to the pKavalues reported in the literature which were obtained by spectroscopy. In this work, it was found that CZE is very suitable for the determination of the pKavalues of the weakly acidic, large ring PAH metabolites. A pKavalue acquired for one of the model compounds by spectrometry gave supporting evidence for the reliability of CZE in obtaining pKavalues for relatively large molecular weight hydroxyl compounds.

ISSN:1082-6076    

DOI:10.1081/JLC-100101689

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Factors were studied which affect the resolution of fibrinogen and fibrinogen degradation products (FDPs) in weak anion-exchange HPLC employing pH gradients. One factor studied was the effect of the buffer capacity of the mobile phase on resolution. A linear pH gradient generated by a gradient chromatofocusing technique, which has an approximately equal buffer capacity throughout the gradient pH range, was found to only marginally separate fragment D and fibrinogen. In contrast, a gradient of an elution buffer of diethanolamine/phosphate, which is strongly buffered in the pI range of fragment D but less so in the pI range of fibrinogen, yielded much better resolution. Another factor studied was the effect of pre-generating a pH gradient within the column prior to chromatography. A pre-generated column pH gradient was found to significantly improve resolution, as a single peak for native fibrinogen was resolved into two peaks. This work also showed different chromatographic profiles for fibrinogen from different commercial sources, indicating different proportions of native and denatured/degraded fibrinogen in the samples.

ISSN:1082-6076    

DOI:10.1081/JLC-100101690

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An anion exchanger based on MFE-Polymer (hydroxy-ethylmethacrylate, HEMA) containing quaternary ammonium functional groups has been used to pack a 150 × 4.6 mm id steel column, and the efficiency of this ion exchanger to preconcentrate phenoxy acid herbicides residues has been studied. The phenoxy acid herbicides studied were 2,4-dichlorophenoxy acetic acid (2,4-D), 4-(2,4-dichlorophenoxy)-butanoic acid (2,4-DB), 2,4,5-trichlorophenoxy acetic acid (2,4,5-T), 2-(2,4,5-trichlorophenoxy)-propanoic acid (2,4,5-TP), and 4-chloro-2-methylphenoxy acetic acid (MCPA). Dicamba (3,6-dichloro-2-methoxybenzoic acid), a benzoic acid herbicide usually used in technical products in mixtures with some of the related phenoxy acids, has also been included in the study. Retention of these herbicides on the referred ion exchanger is possible in aqueous acidic medium, probably because of the high polarizing power of the quaternary ammonium groups over the studied herbicides.

ISSN:1082-6076    

DOI:10.1081/JLC-100101691

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Different attempts to increase retention of strong acids in ion exclusion chromatography are presented. A decrease of the dissociated forms of the sorbent functional groups which increases the retention of strong acids can be achieved either by decreasing the effective charge of the support, or by using a week exchanger as silica, instead of conventionally sulfonated resins.

ISSN:1082-6076    

DOI:10.1081/JLC-100101692

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The published method allows the separation of the four isomers of the anxiolytic 2,3-diazepine derivative, tofisopam. Assignment for the peaks of the two central and two helical isomers is performed by using the chromatogram of the pure tofisopam enantiomers and also considering the conformer-equilibrium was suggested by previous authors. The detection has been made by CD. The in situ CD spectra of the peaks, obtained by stop-flow method, definitely show different chiral character.

ISSN:1082-6076    

DOI:10.1081/JLC-100101693

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

An Ion-Interaction RP-IIR-HPLC method was developed, able to simultaneously separate neutral, basic, and acidic pesticides in a single run. The proposed method was validated by comparison of the results obtained for the same sample by conventional RP-HPLC and GC/MS methods. For this purpose parametrict-,F-,t-paired, and t- for multiple samplesand non parametricWilcoxon matched-pair signed-ranktests were employed. The accuracy of the proposed IIR-RP-HPLC method was evaluated with respect to a lab-made reference sample of spiked tap water.

ISSN:1082-6076    

DOI:10.1081/JLC-100101694

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A high performance liquid chromatographic method with amperometric detection has been developed for the determination of the diuretic xipamide using a μ-Bondapak C18column. The mobile phase consisted of a mixture water:acetonitrile 50:50, 5 mM in KH2PO4/K2HPO4, pH 4.3. The compound is monitored at +1325 mV with an amperometric detector equipped with a glassy carbon working electrode. A liquid-liquid or solid-liquid extraction prior to chromatographic analysis was done to avoid the interferences found in urine matrix. Percentages of recovery were (99.3±4.7) and (99.4±4.2) for liquid-liquid and solid-liquid extraction, respectively. The method developed has a linear concentration range from 0.05 to 0.50 μg/mL, with a reproducibility in terms of relative standard derivation (RSD) for a concentration level of 1 μg/mL of 4% and a quantitation limit of 0.50 ng/mL. The method was applied to the determination of xipamide in tablets and urine obtained from hypertensive patients after the ingestion of Demiax (xipamide 20 mg).

ISSN:1082-6076    

DOI:10.1081/JLC-100101695

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The main alkaloids of certain plants of the Solanacea family, such as atropine and scopolamine, together with the synthetic homatropine and methylhomatropine, are routinely used medicinal agents and have their monographs in the modern pharmacopeias. In these monographs, non selective chemical reactions and/or TLC serve for the detection of “foreign alkaloids, related substances, etc.” impurities.

ISSN:1082-6076    

DOI:10.1081/JLC-100101696

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor