RESUMEN
The enantiomeric separation of albendazole sulfoxide was carried out by simulated moving bed chromatography with variable zones (VARICOL). An overall recovery of 97% was achieved and enantiomeric ratios of 99.5% for raffinate and 99.0% for extract were attained. A total of 880 mg of (+)-albendazol sulfoxide and 930 mg of its antipode were collected after 55 cycles or 11 h of process, resulting in a mass rate of 2 g/day. Furthermore the absolute configuration of the enantiopure compounds was determined for the first time by vibrational circular dichroism (VCD) with the aid of theoretical calculations as (-)-(S) and (+)-(R)-albendazole sulfoxide.
Asunto(s)
Albendazol/análogos & derivados , Cromatografía/métodos , Albendazol/química , Albendazol/aislamiento & purificación , Dicroismo Circular , Conformación Molecular , EstereoisomerismoRESUMEN
A new material based on poly(methyltetradecylsiloxane) (PMTDS) thermally immobilized onto a silica support has been tested as a sorbent for the solid-phase extraction (SPE) from water of several pesticides used in soybean cultivation. The SPE methodology was developed and validated for six of these pesticides (imazethapyr, imazaquin, metsulfuron-methyl, bentazone, chlorimuron-ethyl and tebuconazole) according to the International Conference on Harmonization directives and the results were compared with those obtained with a commercial C18 SPE cartridge. The PMTDS-based sorbent gives results similar to the commercial sorbent with recoveries and precisions in agreement with directives for residue analysis. The quantification limits, after concentration, of all the pesticides evaluated were 1.0 microg L(-1), below the levels imposed by the principal regulatory agencies. The PMTDS-based sorbent preparation is fast, easy and reproducible and the cartridges are less expensive than similar commercial SPE materials.
Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Residuos de Plaguicidas/aislamiento & purificación , Dióxido de Silicio/química , Siloxanos/química , Contaminantes Químicos del Agua/aislamiento & purificación , Residuos de Plaguicidas/clasificación , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Análisis Espectral , Contaminantes Químicos del Agua/clasificaciónRESUMEN
We report herein a new, practical, and economic synthesis of the phosphodiesterase inhibitor Rolipram on a multigram scale as well as the synthesis of new 4-aryl pyrrolidones and beta-aryl-gamma-amino butyric acids (GABA derivatives) employing an efficient Heck-Matsuda arylation of 3-pyrroline with aryldiazonium tetrafluoroborates. Racemic Rolipram was resolved into its enantiomers using chiral simulated moving bed chromatography having the low-cost microcrystalline cellulose triacetate as a chiral stationary phase.
Asunto(s)
Boratos/química , Compuestos de Flúor/química , Inhibidores de Fosfodiesterasa/síntesis química , Prolina/análogos & derivados , Pirrolidinonas/síntesis química , Rolipram/síntesis química , Ácido gamma-Aminobutírico/análogos & derivados , Ácido gamma-Aminobutírico/síntesis química , Boratos/metabolismo , Cromatografía por Intercambio Iónico/métodos , Compuestos de Diazonio/química , Compuestos de Diazonio/metabolismo , Compuestos de Flúor/metabolismo , Prolina/química , Pirrolidinonas/química , EstereoisomerismoRESUMEN
Isolation and purification of bioproducts from crude extracts can be obtained by affinity methods based on reversible binding of a specific molecule to ligand immobilized in a porous matrix. In the present work, nicrospheres based on chitosan matrix, which incorporated aminophenylboronic acid as a derivative, were prepared and characterized, aimed at developing a beta-amylase adsorption process. Kinetic curves and adsorption isotheriru of the crude extracts as well as the breakthrough curves for a frontal chromatographic separation method of a commercial sample of beta-amylase from soybean are presented. These results were compared to similar data obtained with a comercial microspheres gel based-on agarose.