DIFFERENTIAL PULSE-CATHODIC STRIPPING VOLTAMMETRY (DPCSV) FOR SIMULTANEOUS DETERMINATION OF CU, PB, CD AND ZN IN ENVIRONMENTAL SAMPLES

In this study, attempts are being made to modify an existing CSV(Cathodic Stripping Voltammetry) with SW(Square Wave) mode (Colombo et al., 1996) for simultaneous measurement of multi metals in sea water. The modification includes changing the SWCSV to DPCSV options and optimization of ligand and buffer strength to enhance sensitivity by lowering the detection limit. The experiments are being conducted to investigate the potential interference due to presence of multiple elements. The primary objective of this optimization is to be able to measure the heavy metals including Cu, Pb, Cd and Zn in eluent produced from series of column absorption experiments where stationary phases are pure sands, sands+biochars, soils+biochars and mobile phase is upper glacial aquifer water (groundwater from York Campus well) spiked with different levels of Cu, Pb, Cd and Zn. The optimization includes the determination of peak position for different metals in different physical (nitrogen gas flow) and chemical (ligand and buffer strength) conditions. The voltammetric measurements were carried out using a three electrode system which are the mercury working electrode, platinum auxiliary electrode, and an Ag | AgCl | KCl(sol) reference electrode. The autolab voltammeter (Eco Chemie), connected to a hanging mercury drop electrode (HMDE, Metrohm 663 VA stand drop surface area=0.1 to 0.6 mm2) with the method of differential pulse-cathodic stripping voltammetry was used to gain a basic standard for Cu, Pb, Cd, and Zn. Scans containing four resolved peaks corresponding to these metals were obtained using a combination of tris buffer solution (2-Amino-2-hydroxymethyl-propane-1,3-diol) and oxine (8-hydroxyquinoline) in Nanopure water and pure sand column leached water.