Automatic flow analysis method to determine traces of Mn2+ in sea and drinking waters by a kinetic catalytic process using LWCC-spectrophotometric detection

摘要

A new automatic kinetic catalytic method has been developed for the measurement of Mn2+ in drinking and seawater samples. The method is based on the catalytic effect of Mn2+ on the oxidation of tiron by hydrogen peroxide in presence of Pb2+ as an activator. The optimum conditions were obtained at pH 10 with 0.019 mol L-1 27 bipyridyl, 0.005 mol L-1 tiron and 0.38 mol L-1 hydrogen peroxide. Flow system is based on multisyringe flow injection analysis (MSFIA) coupled with a lab-on-valve (LOV) device exploiting on line spectrophotometric detection by a Liquid Waveguide Capillary Cell (LWCC), 1 m optical length and performed at 445 nm. Under the optimized conditions by a multivariate approach, the method allowed the measurement of Mn2+ in a range of 0.03-3514 L-1 with a detection limit of 0.010 mu g L-1, attaining a repeatability of 1.4% RED. The method was satisfactorily applied to the determination of Mn2+ in environmental water samples. The reliability of method was also verified by determining the manganese content of the certified standard reference seawater sample, CASS-4. (C) 2015 Elsevier B.V. All rights reserved.