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Aflatoxin M1 (AFM1) is a toxic metabolite of the fungal product aflatoxin found in milk. For food safety concern, maximum residual limits of AFM1 in milk and dairy products have been differently enforced in many countries. A suitable detection method is required to screen a large number of product samples for the AFM1 contamination. In this study, monoclonal antibodies (MAbs) against AFM1 were generated using a conventional somatic cell fusion technique. After screening, five MAbs (AFM1-1, AFM1-3, AFM1-9, AFM1-11, and AFM1-17) were obtained that showed cross-reactivity with aflatoxin B1 (AFB1) and aflatoxin G1 (AFG1) but with no other tested compounds. An indirect competitive enzyme-linked immunosorbent assay (ELISA) using a partially purified MAb and antigen-coated plates yielded the best sensitivity with the 50% inhibition concentration (IC) and the limit of detection (LOD) values of 0.13 ng/mL and 0.04 ng/mL, respectively. This indirect competitive ELISA was used to quantify the amount of fortified AFM1 in raw milk. The precision and accuracy in terms of % coefficient of variation (CV) and % recovery of the detection was investigated for both intra- (n = 6) and inter- (n = 12) variation assays. The % CV was found in the range of 3.50-15.8% and 1.32-7.98%, respectively, while the % recovery was in the range of 92-104% and 100-103%, respectively. In addition, the indirect ELISA was also used to detect AFM1 fortified in processed milk samples. The % CV and % recovery values were in the ranges of 0.1-33.0% and 91-109%, respectively. Comparison analysis between the indirect ELISA and high performance liquid chromatography was also performed and showed a good correlation with the R of 0.992 for the concentration of 0.2-5.0 ng/mL. These results indicated that the developed MAb and ELISA could be used for detection of AFM1 in milk samples.

Aflatoxin M1 (AFM1), a group I carcinogen, can be found in the milk of animals fed with aflatoxin-B 1-contaminated feedstuff. In this study, we developed and validated a lateral flow immunoassay (LFIA) with the cutoff value of 0.5 μg/L for AFM1 screening. The validation revealed that the assay yielded high sensitivity, selectivity and efficiency with no false positives. Forty-one commercial milk samples were tested for AFM1 by the developed LFIA. However, the developed LFIA could not be applied to milk samples flavoured with chocolate and coffee. Otherwise, all samples gave negative test results.

A novel monoclonal antibody (MAb) against oxytetracycline (OTC) was generated and characterized. The MAb was used in the development of an enzyme-linked immunosorbant assay (ELISA)-based detection system. An OTC-bovine serum albumin (BSA) conjugate was prepared and used in the immunization of mice. A conventional somatic cell fusion technique was used to generate MAb-secreting hybridomas denoted 2-4F, 7-3G, and 11-11A. An indirect competitive ELISA (icELISA) was applied to measure the sensitivity and specificity of each MAb in terms of its 50% inhibitory concentration (IC 50 ) and percentage of cross-reactivity, respectively. MAb 2-4F exhibited the highest sensitivity, with an IC 50 of 7.01 ng/ml. This MAb showed strong cross-reactivity to rolitetracycline, but no crossreactivity to other unrelated antibiotics. When MAb 2-4F was used to detect OTC from shrimp samples, the recoveries were in the range of 82%-118% for an intra-assay and 96%-113% for an inter-assay. The coefficients of variation of the assays were 3.9%-13.9% and 5.5%-14.9%, respectively.