摘要:

The enantiomers of a series of twelve O,O-diethyl, (p-methyl-benzenesulfonamido), aryl(alkyl)-methylphosphonates have been separated by high performance liquid chromatography on a Pirkle model chiral stationary phase. Chromatographic data and a chiral recognition model are presented for the separation of these organic phosphorus enantiomers on the chiral phase. The influence of column temperature and flow rate of mobile phase has been described.

ISSN:1082-6076    

DOI:10.1080/10826079608005503

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A high Performance Liquid Chromatographic method with amperometric detection for the determination of the loop diuretic l-Isopropyl-3-[4 - (3-methylphenylamino)-3-pyridinesulphonyl] urea, torasemide, is reported using a μ-Bondapak C18column and a mobile phase water:acetonitrile (65:35), 5 mM in potassium dihydrogenphosphate/dipotassium hydrogenphosphate at pH 5.3. Eluant is monitored at +1300 mV with an amperometric detector equipped with a glassy carbon working electrode. The method showed a determination limit of 8 ppb and a reproducibility in terms of relative standard deviation lower than 2% in intra-day assays and 5% in inter-day assays. The HPLC-EC method was applied to urine samples obtained from a healthy volunteer. Concentration levels of torasemide at different time intervals were monitorized and results were in agreement with the pharmacokinetic parameters of this diuretic. The determination of torasemide in urine required a liquid-liquid extraction prior to chromatographic analysis due to the interferences found in urine matrix. With this simple clean-up procedure, recoveries around 70% were achieved. Torasemide was directly determined in tablets after dissolution of the powder in a methanolic solution.

ISSN:1082-6076    

DOI:10.1080/10826079608005504

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The influence of different factors on efficiency and peak asymmetry for a wide group of PAHs in micellar liquid chromatography (MLC) is studied. One can see that efficiency increases as the concentration of surfactant in the mobile phase increases. The addition of 2-propanol increases efficiency up to a 15%. The simultaneous effect of temperature and flow rate show the influence of hydrophobicity of solutes on efficiency. H-μ plots show a different behavior of PAHs in MLC as compared to RP-HPLC.

ISSN:1082-6076    

DOI:10.1080/10826079608005505

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Capillary electrophoresis (CE) has established itself as a powerful and widely utilized technique for routine analytical separations, characterized by short run times and high efficiencies. A major drawback to CE is its low concentration sensitivity. Because total system volume is generally only a few μl, the detector flow cell should have a small volume, which imposes a limit on detection sensitivities. In this study, we report a simple method for creating a region of extended path length for absorbance detection in capillary electrophoresis. Up to a six-fold gain in sensitivity, compared to on-column detection, was accomplished when the sleeve-cell was utilized at the detection point.

ISSN:1082-6076    

DOI:10.1080/10826079608005506

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A reliable method is proposed for simultaneous determination of sulfonylureas in various formulation of commercial products by high performance liquid chromatography. HPLC was achieved on a reverse phase C18column by isocratic elution using water (pH 4.3 with acetic acid) / methanol, and detection was by UV absorption at a wavelength of 254nm. This method has been applied for the quality control of sulfonylurea herbicides in the laboratories of agricultural chemical plants.

ISSN:1082-6076    

DOI:10.1080/10826079608005507

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Commercial ethoxylated tributylphenol oligomers were separated according to the number of ethylene oxide (EO) units by reverse phase high performance liquid chromatography on porous graphitic carbon column at different eluent concentration (methanol-water). The retention time increased with decreasing methanol concentration of the eluent and increased with the ethylene oxide unit number. Linear correlation was found between Igk0' and fraction of EO number. Stepwise regression analysis indicated the appearance of the helical form of the oligomers.

ISSN:1082-6076    

DOI:10.1080/10826079608005508

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A high performance liquid chromatographic method with amperometric detection has been developed for the simultaneous determination of two diuretics: triamterene and furosemide, using a μ-Bondapak C18column. The mobile phase consisted of a mixture water:acetonitrile, 30:70, 5mM in KH2PO4/K2HPO4, pH 5.5 pumped at a flow rate of 1 mL/min. The amperometric detector, equipped with a glassy carbon electrode, was operated at +1300 mV.

ISSN:1082-6076    

DOI:10.1080/10826079608005509

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Analysis of sherry wine vinegars using reverse phase HPLC and diode array detection, via direct injection is performed. The technique proved to be useful to study phenolic composition, the identification of major peaks being achieved. The following compounds were detected in all the samples analyzed: gallic acid, caftaric acid, tyrosol, hydroxymethylfurfural and, in almost every sample analyzed, p-coumaroyltartaric glucosidic ester, caffeic acid, p-coumaric acid and caffeic ethyl ester. The results obtained may be helpful to establish a phenolic profile for sherry vinegars which may be used as an origin recognition pattern. These vinegars have been recently awarded their certification brand recognition.

ISSN:1082-6076    

DOI:10.1080/10826079608005510

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Sample preparation techniques for the determination of 4-nonylphenol in water and sediments were optimized using two-level orthogonal array design (OAD). Comparison between the use of cartridge-based solid-phase extraction and membranous disk-based extraction was made for water samples. For sediment samples, microwave-assisted solvent extraction (MASE) was employed. A comparison between MASE and classical soxhlet extraction of spiked samples was also carried out. 4-Nonylphenol was determined using high performance liquid chromatography (HPLC) coupled to both ultraviolet and fluorescence detection

ISSN:1082-6076    

DOI:10.1080/10826079608005511

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We have determined β values of mixed solvents for the 2-propanol/hexane, ethyl acetate/hexane, and methanol/water systems using totally 5 indicator pairs (10 dyes) three of which were synthesized in this study. The variations of β vs. solvent composition for the RPLC solvent system are in a striking constrast with those for the NPLC systems. While a definite maximum was recognized in the plots of β vs. for the NPLC systems, a linear correlation of β with was observed for the RPLC solvent system. The appearance of maximum is probably due to formation of aggregates of the more polar solvent when its composition gets higher.

ISSN:1082-6076    

DOI:10.1080/10826079608005512

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor