Analytical method for simultaneous determination of pesticide and veterinary drug residues in milk by CE-MS.

This study reports a method based on CE-MS/MS detection developed for the multiresidue determination of seven pesticides (amidosulfuron, cyprodinil, cyromazine, imazaquin, pirimicarb, demethyl pirimicarb, procymidone) and eight residues of veterinary drugs (ciprofloxacin, enrofloxacin, sulfacetamide, sulfabenzamide, sulfachlorpyridazine, sulfaquinoxaline, sulfathiazole, sulfisoxazole), whose contents are regulated by the EU Council Regulations no. 396/2005 and no. 2377/90, in animal edible tissues. Milk samples were extracted with ACN and the extract was cleaned up using an Oasis hydrophilic-lipophilic balance SPE cartridge. The proposed method was validated in accordance with the European Commission Decision 657/2002. MS/MS experiments, using an IT analyzer, operating in multiple reaction monitoring mode, were carried out to achieve the minimum number of required identification points. Recovery data were also satisfactory, with values higher than 78% for most pesticides and veterinary drugs extracted from milk spiked at half the maximum residue limit established for the studied compounds. The RSD% (n = 5) were lower than 13 and 15% for intra-day and inter-day assays, respectively. The method was applied to establish the occurrence of the studied pesticides in 100 milk samples, attaining the determination of pesticide and veterinary drug residues in milk in the low microg/kg range.