Simultaneous extraction and catalytic adsorptive stripping voltammetric measurement of Cr(VI) in solid samples.

A fast, simple, sensitive and economical method for Cr(VI) extraction and determination in solid samples was developed and evaluated. The presented protocol for Cr(VI) determination in solid samples allows for simultaneous extraction and determination of Cr(VI) in one step. The procedure is based on a quantitative extraction method in which the complexing properties of diethylenetriaminepentaacetic acid (DTPA) were exploited to extract total Cr(VI) (soluble and insoluble forms) from the solid sample. A catalytic adsorptive stripping voltammetric technique is employed for direct determination of Cr(VI) in the extract. The effects of analytical parameters such as temperature, pH, composition and concentration of the supporting electrolyte (which simultaneously plays the role of extractant), extraction and accumulation time were investigated. The accuracy of the proposed procedure was tested by analyzing certified reference materials CRM 013 Paint Chips and CRM 019 Ash. The results obtained were compared with the results obtained using two other reference extraction procedures. The effects of potentially interfering ions which generally accompany Cr(VI) in natural samples on the Cr(VI) determination, with special notice to Cr(III) interference, are reported.