ONLINE DETERMINATION OF CHROMIUM BY ADSORPTIVE CATHODIC STRIPPING VOLTAMMETRY

To date, the application of adsorptive cathodic stripping voltammetry (ACSV) to chromium determination has commonly involved static systems in a batch approach. The use of ACSV in a dynamic system is reported h ere. The on-line system is described and optimization of the experimen tal parameters discussed, The metal ions were complexed with diethylen etriaminepentaacetic acid and the complex was absorbed, from the flowi ng stream, onto the surface of a glassy carbon electrode, which was pr e-plated, on-line, with mercury. Reduction of the complex, in the pres ence of nitrate, produced a catalytically enhanced reduction current a t -1.27 V (Ag-AgCl). The working limit of quantification was 0.2 ng ml (-1) of Cr-VI (for 60 s deposition), with a relative standard deviatio n of typically 2-3% at the 2 ng ml(-1) level and a determination time of less than 3 min sample(-1).