HEAVY-METAL DETOXIFICATION BY TRIMERCAPTO-S-TRIAZINE (TMT) AS EVALUATED BY A BACTERIAL ENZYME ASSAY

We compared trimercapto-s-triazine (TMT) to ethylenediaminetetraacetat e (EDTA) for detoxification of five selected heavy metals as part of a n effluent fractionation procedure. Toxicity was assessed using a micr obial microplate assay, based on the MetPAD(TM) test kit. The affinity of TMT to four of the metals (Cd, Cu, Hg, Pb) was on the same order o f magnitude as EDTA, as indicated by minimum mole ratios of ligand to metal required for detoxification. The TMT was ineffective against Zn. Both TMT and EDTA were toxic (causing more than 30% inhibition) to th e test bacterial enzyme at concentrations of 3,000 muM or greater. The range of TMT concentrations that detoxified the metals was broader th an that of EDTA. Stimulation of enzyme activity by EDTA could complica te interpretation of test data, a problem not shared by TMT.