Elimination of the Interference of Manganese(ll) in the Analysis of Aqueous Samples Using U.S. EPA Methods 625 and 8270

摘要

It is observed that manganese(II) strongly interferes with the analysis of most acidic components of U.S. Environmental Protection Agency (EPA) Methods 625 and 8270 for aqueous samples because of the oxidation of MnO_2 centre dot yH_2O formed during the alkaline conditions of the extraction process. One part-per-million of Mm ID is sufficient to cause lower recoveries of acidic surrogates and most acidic components, whereas 3 ppm can cause very low to zero recovery of many acidic surrogates and target components. In this study, 102 target semivolatiie organic compounds, regulated by EPA Methods 625 and 8270 or other related regulations, are studied. It is shown that Mn(ll) strongly interferes with 12 semivolatiie organic compounds. Experimental results show that an appropriate amount of EOTA added to samples before the extraction tan completely prevent this interference. It is also demonstrated that EDTA does not have an observable negative influence on the recoveries of the 102 semivolatiie organic compounds.