Development and Validation of an HPLC/MS/MS Method for the Confirmation of Eprinomectin Marker Residue in Bovine Liver Tissue

A liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) method has been developed and validated to detect and confirm the marker residue of eprinomectin (B1a component) in bovine liver when present at levels ≥2400 ng/g. Sample extracts prepared for assay by the LC/fluorescence determinative method (prior to the derivatization step) and standard solutions were used to validate the confirmatory method. The chromatographic retention time of the eprinomectin B1a component and the relative ion intensities of the parent ion ([M + H]+ at m/z 914) and three product ions (m/z 896, 468, and 330) generated by fragmentation of the parent ion are compared to those determined from standards. Keywords: Eprinomectin; residue; confirmatory; bovine liver; LC/MS/MS