Development of solid-phase extraction for triazines: Application to a biological sample

A sensitive extraction method for the concentration of the triazines simazine, atrazine, and ametryn was developed and applied to a biological sample (urine). After protein precipitation with acetonitrile, a further purification using solid-phase extraction (SPE) was carried out. The samples were then analysed by high performance liquid chromatography (HPLC) using a C-18 column and an acetonitrile-water (40: 60, v/v) mobile phase. The pH of the mobile phase was adjusted to 9.0 with NH4OH, the flow-rate was 0.5 mL/min and UV detection was at 220 nm. Recovery values were satisfactory and the method developed can be used for monitoring urine samples of workers exposed to simazine, atrazine, and ametryn, in forensic, veterinary, and environmental toxicologies.26578179

Semi-preparative HPLC separation of terpenoids from the seed pods of Hymenaea courbaril var. stilbocarpa

Column chromatography of the ethyl acetate extract of the seed pod resin of Hymenaea courbaril var. stilbocarpa furnished a fraction containing a mixture of two new clerodanes and a known clerodane diterpene. Due to the similarity of the structures, they could not be separated by ordinary chromatography even using silica gel impregnated with AgNO3. Thus, an intense study was made in order to optimize the semipreparative separation of this mixture by HPLC (high performance liquid chromatograph) using several different stationary and mobile phases. The best conditions for separation of these diterpenes was on octadecyl-bonded silica with methanol: water: formic acid (85:15:1, v/v/v) as mobile phase, flow rate at 2 mL/min, and UV detection at 240 nm. The fractions obtained were analyzed by gas chromatography-mass spectrometry (GC-MS).251596

Methods of extraction and/or concentration of compounds found in biological fluids for subsequent chromatographic determination.

When organic compounds present in biological fluids are analysed by chromatographic methods, it is generally necessary to carry out a prior sample preparation due the high complexity of this type of sample, especially when the compounds to be determinated are found in very low concentrations. This article describes;some of the principal methods for sample preparation in analyses of substances present in biological fluids. The methods include liquid-liquid extraction, solid phase extraction, supercritical fluid extraction and extraction using solid and liquid membranes. The advantages and disadvantages of these methods are discussed.241687

Flavonoids from Lonchocarpus latifolius roots

From the petrol extract of Lonchocarpus latifolius roots, 10 flavonoids were isolated. These included: 3,5-dimethoxy-2',2'-dimethylpyrano-(5',6':8,7)-flavone, 3-methoxy-(2',3':7,8)-furanoflavanone, 3',4'-methylenedioxy-(2',3':7,8)-furanoflavanone, and (2,3-trans-3,4-trans)-3,4-dimethoxy-(2',3':7,8)-furanoflavan, as well as the previously known karanjachromene, Karanjin, lanceolatin B, pongachromene, pongaglabrone and ponganpin. Only nine flavonoids could be quantified through HPLC analysis. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.55778779

Studies on degradation of glyphosate by several oxidative chemical processes: Ozonation, photolysis and heterogeneous photocatalysis

Several different Advanced Oxidation Processes (AOPs) including ozonation at pH 6.5 and 10, photolysis and heterogeneous photocatalysis using TiO(2) as semiconductor and dissolved oxygen as electron acceptor were applied to study the degradation of glyphosate (N-phosphonomethyl glycine) in water. The degree of glyphosate degradation, the reactions kinetic and the formation of the major metabolite, aminomethyl phosphonic acid (AMPA), were evaluated. Ozonation at pH 10 resulted in the maximum mineralization of glyphosate. It was observed that under the experimental conditions used in this study the degradation of glyphosate followed the first-order kinetics. The half-life obtained for glyphosate degradation in the O(3)/pH 10 process was 1.8 minutes.451899

An NMR tool for cyclodextrin selection in enantiomeric resolution by high-performance liquid chromatography

Complexation-induced chemical shifts and diffusion coefficients (HR-DOSY) of enantiomers with native and derivatized cyclodextrins were used for calculations of the apparent binding constants of three cyclohexanone inclusion complexes. Correlations between these data and high-performance liquid chromatography were established, revealing that this approach can be applied as an alternative method to predict enantiomeric discrimination. Copyright (C) 2002 John Wiley Sons, Ltd.40743344