Use of automated solid-phase extraction equipment for the determination ofivermectin residues in animal liver by HPLC

An improvement of the method commonly used for the determination of ivermec tin is proposed. An automatic system is used for the solid-phase extraction column purification stage in order to provide more efficient and fast samp le preparation, prior to separation and quantification by HPLC. Some tests were performed to obtain recovery and repeatability data. The mean recovery for spiked samples (five replicates twice at three concentration levels) w as more than 90% in the concentration range 7.5-30 ng g(-1). The tests for accuracy (five replicates at three concentration levels) gave a standard er ror of -2.0% at the highest and -19.2% at the lowest concentration. Concern ing repeatability data (five replicates twice at three concentration levels ), in the concentration range 7.5-30 ng g(-1) the RSD varied from 9.29 to 2 .15%. The described method was used in a survey on the presence of ivermect in in food-producing animals in two regions of southern Italy; no positives out of 250 liver samples were found.