RESUMEN
The applicability of a rapid and easy multiresidue method for determination of pesticide residues in agricultural products by using liquid chromatography/tandem mass spectrometry (LC/MS/MS) was examined. Pesticide residues were extracted with acetonitrile in a disposable tube using a homogenizer, followed by salting out with anhydrous magnesium sulfate and sodium chloride. The extract was purified with a double-layered cartridge column (graphite carbon black/primary-secondary amine silica gel). After removal of the solvent, the extract was resolved in methanol-water and analyzed with LC/MS/MS. Recovery tests of 99 pesticide residues from 7 agricultural products were performed at 20 and 100 ng/g. Throughout all of the agricultural products tested, 47 pesticides exhibited satisfactory recoveries (70-120%) and relative standard deviations (<20%) at both concentrations. The time for processing of 12 samples to test solutions was approximately 2-3 h. This method could be useful for determination of pesticide residues in agricultural products.
Asunto(s)
Grano Comestible/química , Frutas/química , Residuos de Plaguicidas/análisis , Verduras/química , Cromatografía Liquida , Simulación por Computador , Indicadores y Reactivos , Legislación Alimentaria , Éteres Fenílicos , Propionatos/química , Reproducibilidad de los Resultados , Espectrometría de Masas en TándemRESUMEN
Cytochrome P450(BSbeta) is a peroxygenase that catalyzes the alpha- or beta-hydroxylation of myristic acid by utilizing H(2)O(2). The wild-type enzyme not only hydroxylated myristic acid, but oxidized 3,5,3',5'-tetramethylbenzidine (TMB), a peroxidase substrate, in a myristic acid-dependent reaction. Study of inhibition of hydroxylation of myristic acid by TMB indicates these two substrates compete for the same highly reactive intermediate during the course of their respective reactions. When deuterated myristic acid was used as a substrate to decrease hydroxylation activity, the rate of TMB oxidation increased. This increased rate of TMB oxidation was greatly enhanced when the R242K mutant enzyme bound with deuterated myristic acid was used. These results suggest that there are critical structural elements at the distal active site which determine whether this enzyme acts as a peroxygenase or a peroxidase.
Asunto(s)
Sistema Enzimático del Citocromo P-450/metabolismo , Peroxidasas/metabolismo , Bacillus subtilis/enzimología , Bacillus subtilis/genética , Bencidinas , Dominio Catalítico/genética , Sistema Enzimático del Citocromo P-450/química , Sistema Enzimático del Citocromo P-450/genética , Hidroxilación , Cinética , Mutagénesis Sitio-Dirigida , Ácido Mirístico , Oxidación-Reducción , Peroxidasas/química , Peroxidasas/genética , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Especificidad por SustratoRESUMEN
A rapid and easy multiresidue method for determination of pesticide residues in Chinese dumplings using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. Pesticide residues were extracted with ethyl acetate in the presence of anhydrous magnesium sulfate in a disposable tube using a homogenizer. The extract was concentrated and reconstituted in hexane, followed by acetonitrile-hexane partition to remove lipids. The acetonitrile layer was purified with a double-layered cartridge column (graphite carbon black/primary secondary amine silica gel). After removal of the solvent, the extract was resolved in methanol/water and analyzed with LC-MS/MS. Recovery tests of 99 pesticide residues from Chinese dumpling were performed at 20 and 100 ng/g, and 72 pesticides exhibited acceptable recoveries (70-120%) with low relative standard deviations (<20%) at both concentrations. The time for sample preparation with 12 samples to test solutions was approximately 6 hr. This method could be useful for determination of pesticide residues in the Chinese dumplings.
Asunto(s)
Cromatografía Liquida/métodos , Análisis de los Alimentos/métodos , Residuos de Plaguicidas/análisis , Espectrometría de Masas en Tándem/métodosRESUMEN
A rapid and simple multiresidue method has been established for determination of pesticide residues in processed foods by GC/MS. The pesticides were extracted with ethyl acetate in the presence of anhydrous MgSO(4) in a disposable tube, using a homogenizer. The extract was concentrated and reconstituted in hexane, followed by acetonitrile-hexane partition to remove lipids. The acetonitrile layer was cleaned up with a double-layered SPE cartridge column (graphite carbon black/PSA silica gel). After removal of the solvent, the residue was dissolved in acetone. The test solution was subjected to GC/MS in the EI mode. Recovery tests of 222 pesticides from five kinds of processed foods (dumpling, curry, French fries, fried chicken, fried fish) were performed at two different fortification levels of 0.02 and 0.1 microg/g, and 100 pesticides showed acceptable recovery (70-120%) with low relative standard deviation (Asunto(s)
Análisis de los Alimentos/métodos
, Contaminación de Alimentos/análisis
, Manipulación de Alimentos
, Cromatografía de Gases y Espectrometría de Masas/métodos
, Residuos de Plaguicidas/análisis
RESUMEN
A rapid and simple multiresidue method has been established for determination of pesticide residues in processed foods by GC/MS/MS. The pesticides were extracted with ethyl acetate, and were cleaned up with a double-layered SPE cartridge column (graphite carbon black/PSA silica gel). Recovery tests of 258 pesticides from five kinds of processed foods (dumpling, curry, French fries, fried chicken, fried fish) were performed at two different fortification levels of 0.02 and 0.1 microg/g, and 184 pesticides showed acceptable recovery (70-120%) with relative standard deviation of Asunto(s)
Análisis de los Alimentos/métodos
, Contaminación de Alimentos/análisis
, Manipulación de Alimentos
, Cromatografía de Gases y Espectrometría de Masas/métodos
, Residuos de Plaguicidas/análisis
, Espectrometría de Masas en Tándem/métodos