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

We compared trimercapto-s-triazine (TMT) to ethylenediaminetetraacetate (EDTA) for detoxification of five selected heavy metals as part of an effluent fractionation procedure. Toxicity was assessed using a microbial 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 of 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 the test bacterial enzyme at concentrations of 3,000 muM or greater. The range of TMT concentrations that detoxified the metals was broader than that of EDTA. Stimulation of enzyme activity by EDTA could complicate interpretation of test data, a problem not shared by TMT.