In total 307 egg and 275 liver samples were examined for nicarbazin and 365 eggs for diclazuril over a 30-month period. Enzyme-linked immunosorbent assay methods used for quantification were validated according to European Commission Decision 2002/657/EC. Non-compliant samples were confirmed by LC-MS/MS. Mean diclazuril concentrations in egg samples were 0.31 µg kg⁻¹, which is below the MRL. In only one egg sample, 2.26 µg kg⁻¹ was determined by enzyme-linked immunosorbent assay, although confirmation by LC-MS/MS gave a value of 1.6 µg kg(-1). Mean nicarbazin levels determined were 1.85 µg kg⁻¹ in egg and 21.1 µg kg⁻¹ in liver samples. Four samples, one egg and three livers, yielded elevated concentrations of nicarbazin, but only in the egg sample the LC-MS/MS method confirmed nicarbazin (106 µg kg⁻¹) above the MRL value.
Keywords: ELISA; LC-MS/MS; diclazuril; egg; liver; nicarbazin.