Determination of Ivermectin Residues in Bovine Liver Samples By ELISA and HPLC with Fluorescence Detection

Ivermectin is an anti-parasitic medication frequently used in many food-producing animals. This study aimed to investigate the level of ivermectin residue in liver samples collected from slaughterhouses in Qazvin Province, Iran.
Overall, 88 bovine liver samples were randomly collected and analyzed for detection of ivermectin residues. The samples were analyzed for ivermectin contamination by enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). The samples were extracted using liquid-liquid extraction procedure for the ELISA. Solid phase extraction using a C18 column followed by fluorescence-derivatized with 1-methylimidazole and trifluoroacetic anhydride in acetonitrile were used for the HPLC assay. Recovery values obtained from the HPLC method ranged from 81.3 to 92.5%, with a relative standard deviation of 6.7-12.2%.
First, all samples were screened by the ELISA method. Based on the results, 16 samples (18.2%) contained no detectable levels of Ivermectin residue, while Ivermectin was found in 72 samples (81.8%). In addition, 22 of the positive samples (30.55%) contained high Ivermectin level (>50 ppb). Analysis of the samples by the HPLC method showed that eight samples (9.09%) contained ivermectin levels above the maximum residue limit.
This study demonstrates the presence of different levels of Ivermectin residue in bovine liver samples collected from the Qazvin Province in Iran. Therefore, regulatory authorities should ensure proper withdrawal period before slaughter of the animals.