Optimization for quick, easy, cheap, effective, rugged and safe extraction of mycotoxins and veterinary drugs by response surface methodology for application to egg and milk

A multiclass method was proposed for the simultaneous determination of various classes of veterinary drugs (n = 65), mycotoxins and metabolites (n = 39) in egg and milk by ultra-high performance liquid chromatography-tandem mass spectrometry. The contaminants were extracted by QuEChERS-based strategy including salt-out partitioning and dispersive solid-phase extraction for cleanup further. With the aim of maximizing throughput and extraction efficiency, Plackett-Burman design was employed initially for screening significant variables. And response surface methodology based on central composite design was conducted to achieve optimal conditions in details: 3.35% (v/v) of formic acid in acetonitrile, 1.2 g of NaCl, 0.5 g of anhydrous NaAc, 300 mg of C18 and 140 mg of primary secondary amine. Satisfactory analytical characteristics in validation, in aspects of accuracy (70%-105% for mycotoxins and quinolones, 55%-80% for sulphonamides and 40%-105% for other veterinary drugs), precision (inter-day RSDs < 14%) and sensitivity (LOQs ranged from 0.01 μg/kg to 31 μg/kg), were achieved under the optimized conditions. The matrix effects were evaluated and compensated by the use of matrix-matched calibration curves (R2 > 0.987). In practice, 45 eggs and 30 milk samples were investigated by the established method, of which positive finding aflatoxin in milk and sterigmatocystin in eggs.