Investigation of Charm Test II receptor assays for the detection of antimicrobial residues in suspect meat samples
Charm Test II receptor assays for β-lactams, sulfonamides, (dihydro)streptomycin and erythromycin were applied to 257 bovine muscle and kidney samples, and 215 porcine muscle and kidney samples collected from animals suspected to contain antimicrobial residues. The assays were run in conjunction with Agriculture and Agri-food Canada's routine diagnostic confirmation analyses for suspect samples collected at federally inspected packing plants. All samples were subjected to the Charm Test II receptor assays and thin layer chromatography–bioautography (TLC–BA). Selected samples were quantitatively analysed using a liquid chromatographic method for penicillin G and a thin layer chromatography–fluorescence densitometry (TLC–FD) method for sulfonamides. The Charm Test II assays for β-lactams, (dihydro)streptomycin and erythromycin were an acceptable alternative to the TLC–BA screen for laboratory confirmation of the presence of these compounds, with enhanced sensitivity for (dihydro)streptomycin and erythromycin. In addition, the Charm Test II provided a sensitive screen for sulfonamides as confirmed by the standard TLC–FD procedure. The analysis time, laboratory space and analyst time required to complete the Charm Test II assays is less than that for TLC–BA. Operating costs are similar for both analyses, but the Charm Test II does require capital expenditure for a scintillation counter.