Automatic voltammetric system for continuous trace metal monitoring in various environmental samples

Some recent developments and results in the field of automatic monitoring of electrolabile concentration of zinc and iron in the low mu g/L range in river water, drainage water, and waste water by use of solid dental amalgam electrode (DAM) as a working electrode are reviewed for three different geographical sites representing the mentioned matrixes. At all sites, voltammetric measurements were carried out continuously every 30 or 60 minutes for periods up to 4 months, and compared with total amounts of the metals found by ICP-MS on manually collected samples. In total, the observed concentration ranges analyzed was in the ranges of sub-mu g/L to approximately 30 mu g/L for zinc, and from approximately 1 mu g/L to 150 mu g/L. for iron. Results shows good calibration curves for the metals in the different matrixes (r(avg)(2) = 0.99) with standard deviation within 5%. The voltammetric system showed good stability and gave reliable results which were in a reasonable agreement with ICP-MS measurements for all analyses when comparing the concentration trends. The frequency of maintenance varied from once a week in waste water samples to once a month in river water.