Application of QuEChERS - High Performance Liquid Chromatography with Postcolumn Fluorescence Derivatization (HPLC-FLD) method to analyze Eprinomectin B1a residues from a pour-on conditioning in bovine edible tissues
A QuEChERS in house method for determining the marker residue of eprinomectin (eprinomectin B1a) by HPLC-FLD in bovine tissues and milk provided from treated animals was developed and applied. Briefly: all samples were extracted with acetonitrile using a dispersive SPE purification stage. The ascertained detection limits were 1 μg kg-1 and the quantification limits 2 μg kg-1. Recoveries on tissue samples fortified in the range of 10 μg kg-1 to 200 μg kg-1 were from 80.0% to 87.2%, with variation coefficients between 2.7% to 10.6%. The confirmation of residues in the purified extracts was made by LC-MS/MS after separation on an XTerra MS C18 (10 cm × 2.1 mm, 3.5 μm) column with a mobile phase of acetonitrile / formic acid 0.1% (97:3, v/v) at a flow rate of 0.2 mL min-1 and MRM monitoring of three characteristic ions (m/z 896.1, m/z 467.9 and m/z 329.9), resulting from the fragmentation of molecular ions [M-H]+ (m/z 914.6) of eprinomectin and the comparison of the abundance ratio of fragmented ions was obtained in the booth, sample and standard at comparative concentrations. In conclusion, this method has proven its advantage and versatility as a routine drug residues analysis method.
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