Development of a disposable biosensor for the detection of metam-sodium and its metabolite MITC

A disposable monoenzymatic sensor for the reliable determination of dithioc arbamate fungicides was developed based on aldehyde dehydrogenase inhibitio n. Aldehyde dehydrogenase was immobilized on the surface of a disposable sc reen-printed carbon-paste electrode by using a photocross-linkable poly-(vi nylalcohol) bearing styrylpyridinium groups. Electrochemical oxidation of N ADH was carried out at a potential as low as 0V vs Ag/AgCl using Meldola's Blue as mediator. The sensor was used for the determination of metam-sodium , a soil fumigant, and its main metabolite MITC. It was shown that metam-so dium did not inhibit AIDH while MITC could be detected at levels of 100 ppb . The sensor thus allowed to discrimate between metam-sodium and its toxic metabolite MITC.