RESUMEN
GC-MS data on veterinary drug residues in bovine urine are used for controlling the illegal practice of fattening cattle. According to current detection criteria, peak patterns of preferably four ions should agree within 10 or 20% from a corresponding standard pattern. These criteria are rigid, rather arbitrary and do not match daily practice. A new model, based on multivariate modeling of log peak abundance ratios, provides a theoretical basis for the identification of analytes and optimizes the balance between the avoidance of false positives and false negatives. The performance of the model is demonstrated on data provided by five laboratories, each supplying GC-MS measurements on the detection of clenbuterol, dienestrol and 19 beta-nortestosterone in urine. The proposed model shows a better performance than confirmation by using the current criteria and provides a statistical basis for inspection criteria in terms of error probabilities.
Asunto(s)
Residuos de Medicamentos/análisis , Drogas Veterinarias/orina , Animales , Reacciones Falso Negativas , Reacciones Falso Positivas , Cromatografía de Gases y Espectrometría de MasasRESUMEN
The main objective of this work is to develop a routine quality control method for pesticide residues in cocoa beans, using gas chromatography-mass spectrometry. The investigated pesticides, which are used to control pests in the growing of cacao, are: Acephate, Propoxur, HCH, Heptachlor, Fenitrothion, Pirimiphos-methyl, Aldrin, Dieldrin, pp'-DDE, op-DDE and DDT. Two extraction methods were tested. The first was based on strong attack by concentrated sulphuric acid and later extraction with n-hexane: the investigated residues were Acephate, HCH, Fenitrothion and DDT; recoveries were 68-95% and the detection limits 0.5-10 ppb. The second extraction method was based on the Universal Trace Residue Extractor (UNITREX), which consists of a distillation system for organophosphorus and organochlorine pesticides in fatty samples. The investigated residues were Heptachlor, Pirimiphos-methyl, Aldrin, Propoxur, Dieldrin, op-DDE and pp'-DDE; recoveries were 67-88% and the detection limits 1-10 ppb.