RESUMO
The effectiveness of solid-phase extraction with Florisil for the determination of 12 organochlorine pesticide residues from human serum was examined. Recoveries greater than 84% and coefficients of variation better than 19% were obtained. Others methods, such as column partition and matrix solid-phase dispersion, were compared. The better method provides quantification limits ranging from 1.08 microg/l for gamma-HCH and 37.5 microg/l for p,p'-DDT when capillary gas-liquid chromatography with electron-capture detection is used for the final determination.
Assuntos
Cromatografia Gasosa/métodos , Inseticidas/sangue , Resíduos de Praguicidas/sangue , Acetona , Hexanos , Humanos , Indicadores e Reagentes , Silicatos de Magnésio , Cloreto de Metileno , Sensibilidade e EspecificidadeRESUMO
A derivatization procedure for confirmatory residue analysis of beta2-agonists is described. Methyl (MBA) and butyl (BBA) boronic acids are simultaneously used for the derivatization of tulobuterol, mabuterol, mapenterol, salbutamol, clenproperol, clenbuterol, clenpenterol and bromobuterol by GC-MS determination. A temperature of 55 degrees C during 60 min was selected as optimal temperature-time condition for simultaneous MBA and BBA beta2-agonists derivatization. It was also observed that stability of boronic derivatives was maintained at -20 degrees C over a period of four days. The proposed methodology was tested in urine and it could be applied for confirmatory residue analysis of clenbuterol-like compounds.
Assuntos
Agonistas Adrenérgicos beta/química , Agonistas Adrenérgicos beta/urina , Compostos de Boro/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Animais , Bovinos , Clembuterol/análogos & derivados , Clembuterol/química , Clembuterol/urina , Estabilidade de Medicamentos , Metanol , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Temperatura , Fatores de TempoRESUMO
The earliest pottery yet found in the Western Hemisphere has been excavated from a prehistoric shell midden near Santarém in the lower Amazon, Brazil. Calibrated accelerator radiocarbon dates on charcoal, shell, and pottery and a thermoluminescence date on pottery from the site fall from about 8000 to 7000 years before the present. The early fishing village is part of a long prehistoric trajectory that contradicts theories that resource poverty limited cultural evolution in the tropics.
