摘要:

Terpene compounds include a wide variety of molecules with very different structures and physico-chemical properties. Monoterpenes are of interest because of their volatility and aromatic properties. Inclusion complexation of these molecules with cyclodextrins will lead to chemical and volatility protection and to a possible controlled release. In this study, reversed phase liquid chromatography was used to demonstrate that some terpenes can form inclusion complexes with β-cyclodextrin. The stability of these complexes was studied for aromatic, aliphatic, or acyclic terpenes with various mobile phases.

ISSN:1082-6076    

DOI:10.1081/JLC-100101731

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Countercurrent Chromatography (CCC) utilizes continuous partitioning of solute between two immiscible solvent phases without a solid support. The absence of solid support makes CCC a suitable method for food analysis because it permits analysis of crude and complex materials that are not amenable to conventional solid-supported chromatography. CCC was evaluated for its ability to separate Staphylococcal enterotoxin A (SEA), a common cause of food poisoning, from milk. Although many foods can be analyzed for SEA directly by Western blot analysis, milk samples generally require some purification because the high concentration of milk proteins distorts SDS-PAGE mobility. Milk samples containing SEA were separated by toroidal coil CCC and the fractions were analyzed by Western immunoblotting. Fractions containing SEA were pooled, concentrated by ultrafiltration, and rechecked by Western immunoblotting. Concentrating the fractions increased the sensitivity of Western immunoblotting by approximately an order of magnitude.

ISSN:1082-6076    

DOI:10.1081/JLC-100101732

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Glycoconjugates constitute an important family of macromolecules having a key role in several cellular events. Elucidation of the fine chemical structure of their carbohydrate components is necessary for a deeper understanding of their biological functions. Capillary electrophoresis is a recently developed analytical technique with promising applications in the field of carbohydrate analysis. Various modes of CE have been used for the resolution of carbohydrates. The absence of charge from neutral carbohydrates has been circumvented by ionization of their hydroxyl groups at high pH, complexation with charged agents like borate anions and chemical derivatization. Although the absence of chromophores or fluorophores hinders a sensitive detection by direct UV or fluorescence detectors, indirect detection is a good alternative offering satisfying limits of detection. Electrochemical detectors have also been introduced. Pre-column derivatization of carbohydrates with a wide range of specific chromophores and fluorophores has offered impressive sensitivity gains especially when laser-induced fluorescence detectors are used. In this review, the separation mechanisms of carbohydrates using various CE modes are summarized. The recent developments in detecting carbohydrates and selected applications are also presented.

ISSN:1082-6076    

DOI:10.1081/JLC-100101733

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The separation of actinoids such as Am from lighter lanthanoids has been investigated based on the liquid-liquid extraction principle. An extractant, 5, 8-diethyl-7-hydroxy-dodecan-6-one oxime (LIX 63), is suitable for separation of actinoids heavier than Am from lanthanoids lighter than Eu. On the basis of extraction behavior, multistage separation has been performed by centrifugal partition chromatography (CPC) provided with a series of micro cells. A kerosene solution of LIX 63 was retained in a column as a stationary phase without any solid support. The element substituted for heavier actinoids was chromatographically separated from lighter lanthanoids by CPC.

ISSN:1082-6076    

DOI:10.1081/JLC-100101734

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A new method for the chemical determination of Platelet-ActivatingFactor (PAF) has been developed. The method is based on the derivatizationof the PAF molecule into a fluorescent derivative, through a three step procedureand the determination of the obtained derivative with HPLC combined with afluorescent detector. Initially, PAF is converted to hepta-fluorobutyroyl-derivativewhich is hydrolyzed with water. The hydrolyzed derivative of PAF reacts with7-methoxycoumarin-4-acetic acid to yield a fluorescent derivative of PAF,which is subjected to HPLC analysis on a reverse C18column and measured with a fluorescent detector. The range of linearity andthe detection limit of the method has been detected. The method is linearup to 10 ng PAF with a detection limit of 0.3 ng, at a signal to noise ratioabove 3. This new method was successfully applied to human blood after itsextraction and purification by a published method. Finally, the entire methodhas also been applied to standard phospholipids.

ISSN:1082-6076    

DOI:10.1081/JLC-100101735

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The present work is devoted to the analysis of the phenomenon of “double peaks” of aminoacids in High Performance Liquid Chromatography. Therefore, we have carried out some experiments in order to confirm that the appearance of several peaks from the injection of a single compound was related to different ionic forms of this compound. It could be shown that elution of multiple peaks for L-α-methyldopa did not refer to its degradation products, but to the different ionic species present in the media. The same occurred with its derivative 3-O-methylmethyldopa and with dl-phenylalanine.

ISSN:1082-6076    

DOI:10.1081/JLC-100101736

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In order to evaluate the bioavailability and study the pharmacokinetics of triptolide, an HPLC method was developed for the quantitative determination of this diterpenoid in plasma. The procedure for the plasma assay employed liquid - liquid extraction with chloroform followed by high speed centrifugation. The UV absorbance of the effluent was monitored at 218 nm. An internal standard (acetophenone) was used to calibrate injection and instrument reaction errors. The proposed methodology is sensitive, rapid, and reproducible. The limit of quantitation is 0.005 mg/L in plasma (0.05 mg/L in final solution) and a linear range of determination is observed over the concentration of 0.05 mg/L to 30 mg/L. The inter- and intraday coefficients of variation for the assay of triptolide in plasma were < 16.82 % at low concentration (0.005–0.076 mg/L) and < 8.05% at high concentration (0.152–5.000 mg/L). Recovery of triptolide in plasma is greater than 96.72%.

ISSN:1082-6076    

DOI:10.1081/JLC-100101737

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Synthesis of PD 158771 (Figure 1) involved 4-amino-cyclohexylacetic acid and its ethyl ester intermediates which required purification to obtain the desired correspondingtrans-isomer. HPLC methods were developed for the separation ofcis- andtrans-4-aminocyclohexylacetic acid and the corresponding ethyl esters following pre-column derivatization withNα-(2,4-dinitro-5-fluorophenyl)-L-alaninamide (Marfey's reagent). The chromatographic conditions were varied to achieve optimal separation.

ISSN:1082-6076    

DOI:10.1081/JLC-100101738

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A rapid and sensitive Reversed-Phase High Pressure Liquid Chromatographic (RP-HPLC) method has been developed for the quantitative determination of nitrendipine in human plasma.

ISSN:1082-6076    

DOI:10.1081/JLC-100101739

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

A quick and sensitive method for the determination of AMP, ADP, and ATP levels in mantle tissue of the sea musselMytilus galloprovincialis Lmk. is described. The method uses ion-pair high-performance liquid chromatography with diode array detection, allowing obtaining of the UV absorption spectrum for each peak. Method precision was good. The detection limit for all three nucleotides was 20 pmol (much lower than the minimum concentrations in this tissue).

ISSN:1082-6076    

DOI:10.1081/JLC-100101740

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor