THE SPECIFIC IMMUNOCHEMICAL DETECTION OF 2,4-DICHLOROPHENOXYACETIC ACID AND 2,4,5-TRICHLOROPHENOXYACETIC ACID PESTICIDES BY AMPEROMETRIC CHOLINESTERASE BIOSENSORS

Two specific immunoassays for the detection of 2,4-dichlorophenoxyacet ic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) herbic ides were developed. These methods are based on a specific immunoreact ion of pesticides with antibodies followed by electrochemical detectio n of unbounded pesticides by its inhibition effect on the amperometric cholinesterase biosensor. The total time of assay is less than 20 min . The antibodies are used in solution or immobilised on the nitrocellu lose membrane. The immobilised antibodies could be regenerated several times and are stable for at least 30 days. The dynamic ranges of dete ction of 2,4-D and 2,4,5-T are 1x10(-11)-5x10(-7) M and 5x10(-11)-5x10 (-7) M, respectively. The developed method was applied for 2,4-D deter mination in milk without sample pre-treatment.