DEVELOPMENT OF A DISPOSABLE BIOSENSOR FOR THE DETECTION OF METAM-SODIUM AND ITS METABOLITE MITC

A disposable monoenzymatic sensor for the reliable determination of dithiocarbamate fungicides was developed based on aldehyde dehydrogenase inhibition. Aldehyde dehydrogenase was immobilized on the surface of a disposable screen-printed carbon-paste electrode by using a photocross linkable poly-(vinylalcohol) bearing styrylpyridinium groups. Electrochemical oxidation of NADH 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 metamsodium, a soil fumigant, and its main metabolite MITC. It was shown that metam-sodium did not inhibit AlDH while MITC could be detected at levels of 100 ppb. The sensor thus allowed to discrimate between metam-sodium and its toxic metabolite MITC.