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Ascari J.,Laboratorio Nacional Agropecuario LANAGRO | Dracz S.,Laboratorio Of Residuos Of Medicamento Veterinarios | Santos F.A.,Laboratorio Of Residuos Of Medicamento Veterinarios | Lima J.A.,Laboratorio Of Residuos Of Medicamento Veterinarios | And 2 more authors.
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment

A quantitative liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the simultaneous analyses of malachite green (MG), crystal violet (CV) and its major metabolites, leucomalachite green (LMG) and leucocrystal violet (LCV) residues in fish and shrimp samples has been validated. Fish and shrimp samples were extracted with citrate buffer/acetonitrile, and the extracts were purified on strong cation-exchange (SCX) solid-phase extraction (SPE) cartridge. After conversion of LMG into MG using a post column oxidation reactor containing lead (IV) oxide (PbO2), the effluents were analysed. Residues were analysed using positive-ion electrospray ionisation (ESI). Identification and quantification of analytes were based on the ion transitions monitored by multiple reaction monitoring (MRM). Validation of the method was carried out in accordance with the Decision 2002/657/EC, which establishes criteria and procedures for the validation of methods. The following parameters were determined: decision limit (CCα), detection capability (CCβ), linearity, accuracy, precision, selectivity, specificity and matrix effect. The decision limits (CCα) for MG, LMG, CV and LCV were 0.164, 0.161, 0.248 and 0.860 μg kg-1. The respective detection capabilities (CCβ) were 0.222, 0.218, 0.355 and 1.162 μg kg-1. Typical recoveries (intermediate precision) in shrimp, for MG, CV, LMG and LCV for 2.0 μg kg-1 level fortified samples using the optimised procedure were in the range 69%, 97%, 80.3% and 71.8%, respectively. The findings demonstrate the suitability of the method to detect simultaneously MG, CV and its metabolite (LMG and LCV) in fish and shrimp. © 2012 Taylor & Francis. Source

Magalhaes C.G.,Laboratorio Of Residuos Of Medicamento Veterinarios | De Paiva C.R.,Laboratorio Of Residuos Of Medicamento Veterinarios | Botelho B.G.,Laboratorio Of Residuos Of Medicamento Veterinarios | De Oliveira A.M.G.,Laboratorio Of Residuos Of Medicamento Veterinarios | And 5 more authors.
Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment

Premi®Test, a microbial inhibition test for the screening of antimicrobial residues, was validated according to the criteria established by Decision 2002/657/EC. Sensitivity, detection capability (CCβ), specificity, selectivity, robustness and applicability were evaluated. The methodology involves the technique of solvent extraction, which increases the detection capability of the test for a wider range of antibiotics. The following CCβ values in poultry muscle were found: penicillin G ≤ 12.5 μg kg-1, total sulfonamides ≤75 μg kg-1, erythromycin 75 μg kg-1 and lincomycin 50 μg kg-1. The detection capability of chlortetracycline was equal to its maximum residue limit (100 μg kg-1) and the method did not detect gentamicin (1000 μg kg-1), for which no MRL is established in poultry muscle. Specificity evaluated in relation to different analytes and matrices did not detect any interferences in the tests results; whilst the robustness showed that the pH neutralisation point of the extract affects the analytical results and the kits' performance. Only the screening of tetracyclines requires the analysis of extracts without pH neutralisation. The results of the validation process showed that this method is acceptable for screening β-lactam, sulfonamide and macrolide antimicrobial groups in the National Residues and Contaminants Control Programme (PNCRC), and that for this it is fit for purpose. © 2012 Taylor & Francis. Source

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