ABSTRACT
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.
Subject(s)
Chromatography, Gas/methods , Insecticides/blood , Pesticide Residues/blood , Acetone , Hexanes , Humans , Indicators and Reagents , Magnesium Silicates , Methylene Chloride , Sensitivity and SpecificityABSTRACT
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.
Subject(s)
Adrenergic beta-Agonists/chemistry , Adrenergic beta-Agonists/urine , Boron Compounds/chemistry , Gas Chromatography-Mass Spectrometry/methods , Animals , Cattle , Clenbuterol/analogs & derivatives , Clenbuterol/chemistry , Clenbuterol/urine , Drug Stability , Methanol , Reproducibility of Results , Sensitivity and Specificity , Temperature , Time FactorsABSTRACT
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.
