Microdetermination of mercury using silver and copper ion selective electrodes with silver-dithiooxamide and copper-diethyldithiocarbamate loaded polyurethane foams

Summary

Microdetermination of Mercury Using Silver and Copper Ion Selective Electrodes with Silver-Dithiooxamide and Copper-Diethyldithiocarbamate Loaded Polyurethane Foams

Low levels of mercury(II) are determined by passing their aqueous solutions at pH 1–3 through a column containing silver-dithiooxamide or copper-diethyldithiocarbamate loaded polyurethane foam, followed by monitoring the silver(I) and copper(II) ions released in the effluent with the solid state silver and copper ion selective electrodes, respectively. The rate of the exchange reactions is fast (<3 min) and the efficiency of displacing silver(I) and copper(II) ions is high (>98%). The calibration plots show slopes of 59 and 29 mV/concentration decade of mercury on using the silver and copper sensors, respectively. Determination of 20 ng/ml to 200μ/ml of mercury(II) in aqueous solutions shows an average recovery of 98.4% and a mean standard deviation of 2%. Many cations and anions do not interfere. Some organomercury compounds are similarly determined after a prior decomposition in an oxygen-filled flask. Results with an average recovery of 98.4% (mean standard deviation 1.9%) are obtained with 10 structurally different mercury compounds.