Evaluation of Rapid Test Methods and HPLC for Antibiotic Residue Analysis in Raw Milk Samples

In this study, the methodological performance of three antibiotic residue screening test kits based on different principles were evaluated in artificially contaminated raw milk samples with beta-lactams including ampicillin, amoxicillin, penicillin G and cloxacillin. No false positive result was obtained with immunoreceptor and enzymatic-based test kits in raw milk samples without artificial contamination. However, a false positive result was obtained from one sample using the microbial inhibition-based test kit. At maximum residue limits of Turkish Food Codex, the highest sensitivity rate was obtained from the immunoreceptor-based test kit. The performance of enzyme-based test kit at maximum residue limits was found as insufficient. HPLC method used herein was based on the C18 solid phase extraction and ultraviolet detection at 325 nm of residues derivatized with benzoic anhydride and 1,2,4-triazole mercuric chloride solution. Detection limits of the method were 8, 8, 6 and 11 μg/kg for ampicillin, amoxicillin, penicillin G and cloxacillin, respectively. The mean recovery rates ranged from 67.7 % to 76.6 %. Limits of detection using chromatographic method were found as exceeding the Turkish and European MRLs for ampicillin, amoxicillin and penicillin G.