摘要:

Capillary electrophoresis (CE) applied to the analysis of single cells makes possible the study of the composition of the building block of life, the cell. CE is uniquely suited for the analysis of single cells because ultrasmall samples can be injected, separated, and detected. For instance, CE is capable of detecting femtomole (10−15mole) to attomole (10−18mole) quantities from nanoliter (10−9liter) sample sizes.[1]

ISSN:1082-6076    

DOI:10.1081/JLC-100101502

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The polymorphism of rabbit liver metallothionein RL and of its two isoforms RL-1 and RL-2 has been studied by means of reverse phase HPLC with on-line diode array (DAD) and electrochemical (EC) detection. Separations have been carried out in an acidic mobile phase (TFA). Using the typical UV absorption characteristics of MT, as well as the electrochemical response of the various peaks and comparing the morphology of the chromatograms obtained with a gradient at pH 3 and at pH 2, we reached the following conclusions: RL-1 has three subisoMTs which are apoforms at pH 3 and four other Cu, Cd metalloforms; RL-2 has a less complex polymorphism with one major and one minor subisoMTs under apoform at pH 3; RL has four main subisoMTs which are apoforms at pH 3, coming either from RL-1 or from RL-2 and two main other metalloforms including a pure Cu form not found in the isoforms. In all three MTs, an extra peak has been identified by its non MT-type UV spectrum, its time-dependence increase, its total lack of electrochemical response, and its larger variation of retention time with increasing temperature. This could be a degradation product of MT.

ISSN:1082-6076    

DOI:10.1081/JLC-100101503

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A Chirobiotic T™ column was used for the direct separation of AMPA receptor antagonist LY293558 and the undesired enantiomer LY293559 in bulk drug substance. High performance liquid chromatography (HPLC) separation of the enantiomers was optimized using reversed phase and hydrophilic interaction chromatography (HILIC) by varying the organic composition of the mobile phase. Baseline resolution was achieved allowing accurate, trace level quantitation of the undesired enantiomer in the optically pure bulk material. Because the analytes lack a sufficient ultraviolet chromophore, an evaporative light-scattering detector (ELSD) was used to enhance detection. The ELSD was capable of obtaining detection limits as low as 0.1% of the undesired enantiomer. Additional experiments were conducted to assess the linearity, precision, and accuracy of the HPLC-ELSD system.

ISSN:1082-6076    

DOI:10.1081/JLC-100101504

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Amylose tris (3,5-dimethylphenylcarbamate) coated onto APS-Hypersil (5 μm particle size and 120 Å pore size) was used under normal, reversed-phase and polar-organic conditions for the enantioseparation of six racemates of different classes. The CSP was not altered when going from one mobile phase to another. All compounds were enantioresolved within the elution modes with excellent selectivity factor. The simultaneous analysis of metyrapol enantiomers and metyrapone on reversed-phase conditions and the separation of the enantiomers of omeprazole in human plasma in the polar-organic mode of elution are also described.

ISSN:1082-6076    

DOI:10.1081/JLC-100101505

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A simple and sensitive HPLC (high performance liquid chromatography) method has been developed for the qualitative and quantitative analysis of several CNS (central nervous system) drugs in clinical and forensic toxicology. The leading conditions were studied, namely parameters such as mobile phase pH, organic modifier percentage, and salt concentration. An isocratic HPLC elution, using a mobile phase composed of acetonitrile and pH 2.8 aqueous tetramethylammonium perchlorate and a C8 reversed phase column as the stationary phase, was found to be convenient for the separation of several CNS drugs, and for their detection and quantitation. The identification of the drugs was assured using their relative retention times, together with the peak area ratios at two different wavelengths (230 and 270 nm). A quick pre-treatment of the plasma samples, based on a SPE (solid phase extraction) procedure, with good extraction efficiency and satisfactory selectivity was developed. Under these conditions, a mixture of fifteen CNS drugs (including antipsychotics, antidepressants and antiepileptics) and some selected active metabolites, was well separated for identification and quantitative determination purposes.

ISSN:1082-6076    

DOI:10.1081/JLC-100101506

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The enantiomeric separation by chiral high performance liquid chromatography of derivatized and underivatized α-methyl α-amino acids was achieved by two different methods. A cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phase column (Daicel Chiralcel OD) was used to resolve N-benzyloxycarbonylated methyl esters. Excellent separations of enantiomers were achieved with all the α-methyl α-amino acids examined. A column packed with octadecylsilanized silica coated with N,S-dioctyl-d-penicillamine as a chiral ligand-exchange phase (Sumichiral OA-5000) was also used to resolve the underivatized amino acids. Excellent to good separations of enantiomers were achieved with a variety of underivatized α-methyl α-amino acids carrying aliphatic or aromatic side-chains by optimizing the amount of the organic component and the concentration of the copper(II) ion in the hydro-organic eluent.

ISSN:1082-6076    

DOI:10.1081/JLC-100101507

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

An improved HPLC procedure for separating ciprofloxacin and its four metabolites, M1, M2, M3, M4 in urine, was developed. The procedure used is reversed phase chromatography, the stationary phase being the C18-column, followed by quantification using a UV detector. The mobile phase is a mixture of isopropanol, acetonitrile, tetrabutylammonium bromide (TBABr), heptanesulfonic acid (HSA), and 0.05% triethylamine, (adjusted to pH=3.0 with phosphoric acid.) In the process of determining the optimum separation condition, the effect of each ion-pairing reagent on the retention of all analytes was investigated and explained as well. This method involves an off-line solid phase extraction, using C18Sep-Pak cartridges for ciprofloxacin and its metabolites in urine. The desorption condition is investigated by using different kinds of organic solvents, or a mixture of organic solvents and phosphate buffer, adjusted to different values of pH. At the optimum desorption condition, all analytes show a recovery rate over 90%. Based on this optimum condition, this method was applied to pharmacokinetic study of solutes in urine sample.

ISSN:1082-6076    

DOI:10.1081/JLC-100101508

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A simple method for the determination of zinc bacitracin in feed is presented. The samples were extracted with methanol-hydrochloric acid and 1 mL of the supernatant was evaporated to c. 50 μL. After adding water and mixing, the water layer was cleaned up using LMS solid phase extraction columns, and injected to the liquid chromatography-atmospheric pressure ionization ion spray. The lower limit of quantification was 4 mg/kg in chicken and swine feed.

ISSN:1082-6076    

DOI:10.1081/JLC-100101509

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

This article describes an HPLC method for routine samples analysis of laboratory scale anaerobic immobilized sludge reactors used for degradation of pentachlorophenol (PCP) in synthetic wastewater. The method was developed to quantify pentachlorophenol and six chlorophenol isomers produced during the degradation of pentachlorophenol by anaerobic bacteria. The validated method was used for anaerobic reactor samples and was able to quantify the chlorophenol intermediates produced.

ISSN:1082-6076    

DOI:10.1081/JLC-100101510

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A single column, stability indicating, Ion Chromatographic method has been developed for the determination of Soluble Fluoride and Monofluorophosphate (MFP) in dental cream. The limits of detection (3x signal-to-noise) for Fluoride and MFP in dental cream are 5.0 ppm and 87 ppm (wt./wt.), respectively, using the sample preparation procedure described. These LODs correspond to operating concentrations of F and MFP of 0.05 ppm and 0.87 ppm (wt./vol), respectively. The method is linear for F−(r = 0.9998) over an operating range of 1.0 to 4.5 ppm (wt./vol) (40%–180% of 2.5 ppm target) and for MFP (r = 0.9999) over an operating range of 35.7 to 66.3 ppm (wt/vol) (70%–130% of 51.0 ppm target). Both anions (MFP and F) were found to have no interference with a placebo dentifrice and each passed resolution and tailing factor requirements of R ≥ 2.0 and T<1.5. Quantitative recoveries were obtained for both species from placebos spiked with 70, 100, and 130% of target. Twenty replicate preparations and analyses of a homogenized commercial sample, conducted by two operators over the course of 4 days, showed agreement to within 5.5%RSD for F and 2.23%RSD for MFP.

ISSN:1082-6076    

DOI:10.1081/JLC-100101511

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor