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-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) herbicides were developed. These methods are based on a specific immunoreaction of pesticides with antibodies followed by electrochemical detection 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 nitrocellulose membrane. The immobilised antibodies could be regenerated several times and are stable for at least 30 days. The dynamic ranges of detection 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 determination in milk without sample pre-treatment