Biosensors & Bioelectronics
Electrochemical immunosensors for determination of the pesticides 2,4-dichlorophenoxyacetic and 2,4,5-tricholorophenoxyacetic acids
Two immunochemical sensors are described for detection of the pesticides 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T).
The assay monitors the competitive binding of free pesticide and pesticide-peroxidase conjugate with antibodies immobilized on a graphite electrode, by measurement of peroxidase activity in the immune complexes on the electrode surface.
5-aminosalicyclic acid and H2O2 are used as substrates. An automated potentiometric device measures changes in redox potential during the peroxidase reaction.
The assay parameters were optimized to achieve detection limits of 40 ng/ml 2,4-D and 50 ng/ml 2,4,5-T (in both water and serum).
The total time required to perform the assay (including electrode regeneration) was 12 min, compared to about 2 h for solid-phase enzyme immunoassays. The electrode life extends to 60 sequential measurements.
The sensors therefore appear suitable for medical and ecological applications