摘要:

Capillary electrophoresis methods are reported for the determination of trace levels of substances possibly present as contaminants on equipment used in pharmaceutical manufacturing. A previously reported method for the determination of a range of basic drugs was optimised through use of internal standards and a shorter length capillary. This method was used to establish an optimised extraction procedure through analysis of solutions containing a range of drugs with different solubilities. A CE method for the trace level analysis of a range of different acidic drugs was shown to be capable of achieving acceptable precision and sensitivity. Levels of detergent solution residue were monitored by quantifying potassium levels using indirect UV detection. These methods are in routine use within our laboratories.

ISSN:1082-6076    

DOI:10.1080/10826079808006586

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The difference of the relation of molecular weight (MW) and retention volume of narrow polystyrene (PS) samples from broad ones in the size exclusion chromatography - light scattering (LS)/refractive index (RI) detectors is discussed. Effects of interdetector delay volume on the relation was serious and the approach to adjust the interdetector delay volume so as to get a plateau relation of MW and retention volume for PS samples with a narrow MW distribution was proposed. The interdetector delay volume was found to be a function of MW. PS samples with a broad MW distribution had the similar relation of MW and retention volume to the calibration curve constructed with PS standards with narrow MW distributions; and the MW averages obtained by the LS/RI approach gave the comparable values to those calculated by a calibration curve method.

ISSN:1082-6076    

DOI:10.1080/10826079808006587

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Cationic lipid-mediated gene transfer represents a promising approach for the treatment of a number of diseases. Since the successful introduction of DOTMA:DOPE (Lipofectin), a variety of cationic lipids have been developed for use in gene transfer. Some of the more active cationic lipid formulations, including GL-67:DOPE, DC-chol:DOPE, DMRIE:DOPE and DOTAP, have been used in human clinical trials. It is of critical importance to develop robust analytical methods for the determination of the chemical purity of these formulations. We report here efficient, sensitive, and reproducible reversed-phase HPLC methods for use in determining the chemical purity of cationic lipid formulations. GL-53:DOPE, GL-67:DOPE, DMRIE:DOPE, DC-chol:DOPE, GAP-DLRIE:DOPE, DOTMA:DOPE (Lipofectin), DDAB:DOPE (Lipofectace), DOSPA:DOPE (Lipofectamine), DOGS (Transfectam), and DOTAP were analyzed by HPLC on C8 or C18 bonded phase columns with aqueous/mixed organic mobile phases containing trifluoroacetic acid and with ELSD detection in the gradient elution mode. Baseline resolution of the components of the GL-53:DOPE formulation was achieved by optimization of the solvent system and gradient profile. Capacity factors (k') of the cationic lipids were greatly affected by the end-capping chemistry of the C18 bonded phases. The calibration curves for GL-53, DC-chol, DMRIE, and DOPE were determined in the range of 1.6–200.0 μg. The detection limits for these compounds were determined to be 0.4–1.6 μg

ISSN:1082-6076    

DOI:10.1080/10826079808006588

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The enantiomeric chiral separation of propranolol and several aryloxyaminopropan-2-ol analogs is studied using two cellulose-type chiral stationary phases (CSPs) namely Chiralcel OF and Chiralcel OC and one amylose type chiral stationary phase (CSP), Chiralpak AD. The results showed base-line separation for all the compounds studied using amylose tris (3,5-dimethylphenyl carbamate) known as Chiralpak AD in comparison to the cellulose tris (4-chlorophenylcarbamate) known as Chiralcel OF which showed a significant decrease in the selectivities for most of the compounds, while partial or no separation were obtained using cellulose tris (phenylcarbamate) known as Chiralcel OC.

ISSN:1082-6076    

DOI:10.1080/10826079808006589

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Recently, several liquid chromatographic methods for the assay of erythromycin base were developed and are being considered for the routine assay of erythromycin. In this study, we developed simple and rugged liquid chromatographic methods for the assay of erythromycin salts and esters, and used these methods for the assay of erythromycin estolate, erythromycin ethylsuccinate, erythromycin stearate, erythromycin gluceptate, and erythromycin lactobionate in bulk and pharmaceutical formulations. The HPLC methods proved to be simple, sensitive, versatile, and rugged. The developed methods provide an attractive alternative to current official microbiological methods. The HPLC assay results for all commercial erythromycin products tested comply with the USP Antibiotics-Microbial assay specification.

ISSN:1082-6076    

DOI:10.1080/10826079808006590

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A sensitive high performance liquid chromatographic assay was developed for the determination of caffeine and its dimethylxanthine metabolites in human plasma. Caffeine, paraxanthine, theophylline, and theobromine were extracted from 0.5 mL of matrix with methylene chloride. Separation of the analytes was achieved using a mobile phase consisting of 0.1 M sodium acetate pH 4.5, methanol, tetrahydrofuran, and distilled water (10:6.5:1.4:82.1, v/v) and a Microsorb MV C18analytical column with UV detection at 274 nm. Excellent linearity was observed for each analyte over the concentration range of 20 – 8000 ng/mL.

ISSN:1082-6076    

DOI:10.1080/10826079808006591

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A method for extraction and determination of trace amounts of Carbaryl, Baygon, Methiocarb, and Methiocarb sulfoxide in lettuce and apple samples is described. The arrangement liquid chromatography-particle beam-mass spectrometry offers the possibility of confirmation and determination of these carbamates at concentrations lower than those admitted by the European Union. Recoveries of carbamates at the 0.16–4.9 mg/kg level were between 53 and 76% with standard deviation between 6 and 12% (n = 5). Detection limits for analytes single ion monitoring mode were 5, 30, 10, and 20 ng for Methiocarb sulfoxide, Baygon, Carbaryl, and Methiocarb, respectively.

ISSN:1082-6076    

DOI:10.1080/10826079808006592

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Triglyceride composition of rat liver was analyzed by HPLC with a non-linear elution gradient of acetone in acetonitrile using a light-scattering detector. Triglyceride molecular species were predicted by means of simple and multiple linear regression analysis between the log k' of the HPLC peaks and molecular variables, equivalent carbon number (ECN) of the possible triglycerides, and chain length (CL) and number of double bounds (DB) of each of the fatty acids in the glycerol molecule.

ISSN:1082-6076    

DOI:10.1080/10826079808006593

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Chlordane is a polychlorinated mixture that was used as a long-lived pesticide and now is considered a potential endocrine-disrupting compound. The Environmental Sciences Division is involved in modernizing methods for a number of analytes that are potential target substances for dietary studies, endocrine disrupter studies, Superfund site monitoring, and human exposure studies. In this work, chlordane is determined in soils using each of three different liquid phase/supercritical fluid (CO2) extractions followed by a two-dimensional chromatographic separation based on high performance gel permeation chromatography (HPGPC) followed by GC/electron capture detection (GC/ECD) and GC/electron capture negative ion mass spectrometry (GC/EC NIMS). Liquid phase extractions were carried out using accelerated solvent extraction, supercritical fluid extraction, and Soxhlet extraction. The preparative liquid chromatographic part of the work is used in an off-line fractionation mode of HPGPC. Further cleanup is afforded by solid-phase extraction using silica cartridges. Soils spiked at 2 ppm, 0.2 ppm, and 0.02 ppm were quantitated using GC/ECD and GC/EC NIMS with recoveries usually greater than 80%. Soil from a Superfund site and a standard reference material sediment were analyzed as examples of real samples. The modernized methodology developed in this work should offer improved approaches for Superfund analyses and for monitoring methods used in determining potential exposure to endocrine-disrupting compounds while minimizing solvent usage compared to previous methodology.

ISSN:1082-6076    

DOI:10.1080/10826079808006594

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A rapid modified high performance liquid chromatographic (HPLC) method was developed for the analysis of the benzimidazole fungicide thiabendazole (TBZ) in fresh produce. Changes were in the extraction technique and HPLC mobile phase. TBZ was extracted from the produce by either polytroning 10 g in 20 mL of methanol for 3 minutes or shaking, by hand, a 5 or 10 g sample in 20 mL of methanol for 10 minutes. A 50 μL aliquot was injected directly into an isocratic fluorescent HPLC system. Total analysis time ranged from 8 to 15 minutes per sample depending upon the extraction procedure employed. Percent recoveries averaged 90% with excellent reproducibility (%CVs from 0 to 18). For enzyme linked immunosorbent assay (ELISA) confirmation a 0.1 mL aliquot of the sample was removed and evaporated to dryness under air. The residue was dissolved in water before performing the ELISA.

ISSN:1082-6076    

DOI:10.1080/10826079808006595

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor