Abstract: ObjectiveTo prepare monoclonal antibody against aflatox in M₁ and develop indirect competitive enzymelinked immunosorbent assay for detection of aflatox in M₁.MethodHybridoma cell line excreting monoclonal antibody against aflatox in M₁ was produced using B cell hybridoma technique and develop indirect competitive enzyme-linked immunosorbent assay for detection of aflatox in M₁.ResultsOne hy bridoma cell line excreting monoclonal antibodies against aflatox in M₁ coded 2F2 was obtained by fusing murine Sp2/0 cells with spleen cells from BALB/c mice immunized with A FM₁-BSA conjugate.The monoclonal antibody produced by the hybridoma cell were tested for subtype and designated as IgG₁ for 2F2.The affinity of IgG in purified ascites yielded by hybridoma cell was 2.8×10^-11 mol/L.The monoclonal antibody obtained in the present study was specific to aflatoxin M₁,because of lightly cross reactions among the monoclonal antibodies against aflatox in M₁ with the analog ues of aflatox in B₁,aflatoxin B₂,aflatox in G₁,aflatox in G₂ and aflatox in M₂ were found.The limit of detect ing concentr at ion of aflatox in M₁ was 0.07 ng/ml.The linear range of standard curve was 0.02~2 ng/ml and the linearequation was y=-0.436 4x+0.269 3(R²=0.994 9).The recovery of aflatox in M₁ was betw een 72.5% ~131.3%.ConclusionThe monoclonal antibody obtained in the study was of relatively high specificity to aflatox in M₁,and a simple fast sensitive indirect competitive enzyme-linked immunosorbent assay for the detection of aflatox in M₁ was developed.