Multi-residue methodology for the determination of 16 coccidiostats in animal tissues and eggs by hydrophilic interaction liquid chromatography - Tandem mass spectrometry.

A simple, sensitive and efficient confirmatory method was developed and validated for the determination of 16 coccidiostats in animal tissues and eggs using hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS). The sample preparation consisted of a solid-liquid extraction with ACN and dispersive SPE cleanup with MgSO4 and C18. Analysis was realized in an Acquity BEH HILIC silica column, in SRM mode. Both positive and negative ionization was performed, using polarity switching. Isocratic elution was used with a mobile phase of ACN: aqueous ammonium formate 1 mM with 0.1% formic acid (80:20, v/v). Method validation was performed in eggs, poultry, bovine, ovine, porcine and rabbit tissue and exceptionally low LODs were achieved, varying from 0.004 μg kg-1 (decoquinate in porcine tissue) to 0.560 μg kg-1 (halofuginone in eggs). The developed methodology was applied in 82 muscle and egg samples through the Greek National Residue Control Plan for coccidiostats.