Polyether ionophores residues in Minas Frescal cheese by UHPLC-MS/MS.

An analytical method was developed and validated for the determination of three polyether ionophores (monensin, lasalocid, and salinomycin) in 60 samples of Brazilian Minas Frescal cheese by UHPLC-MS/MS. Linearity ranged from 1 to 8 µg kg-1 for monensin and salinomycin, and from 0.50 to 4 µg kg-1 for lasalocid. Limits of detection and quantitation were 0.50 µg kg-1 and 1 µg kg-1, respectively, for both monensin and salinomycin, and 0.25 µg kg-1 and 0.50 µg kg-1, respectively, for lasalocid. Recoveries were between 69% and 84% with coefficients of variation up to 16.28% for repeatability and 13.79% for intermediate precision. A total of 60 samples of Minas Frescal cheese were analysed and only monensin residues were found. Monensin was detected in 55% of the samples and quantified in 5 of them at mean levels varying from 1.00 to 1.73 µg kg-1. The proposed method demonstrated the suitability for monitoring these substances in cheese.

Applicability of MALDI-TOF MS for determination of quinolone residues in fish.

MALDI-TOF MS approach for determination of six quinolones residues in fillets of pangasius (Pangasionodon hypophthalmus) was studied, considering that is a very sensitive analytical technique with simple and high-throughput operation, contributing to knowledge regarding application of this technique to the determination of small-molecular-weight organic compound residues in foods. LIFT-MS/MS showed to be a successful approach to identify the presence of all quinolone residues in the fish fillet, at their respective MRL level. This study opens an important field of research for the development of simple and high-throughput bioanalytical screening methods for the determination of veterinary drug residues in foods.