Rotating disk sorptive extraction of cu-bisdiethyldithiocarbamate complex from water and its application to solid phase spectrophotometric quantification

Abstract

This study demonstrates the first use of polydimethylsiloxane (PDMS) immobilized on a rotating disk for the extraction of copper from aqueous matrices and its subsequent direct determination by solid phase UV-Visible spectrophotometry. To accomplish the solid-phase extraction and the direct solvent-free spectrophotometric measurement, sodium diethyldithiocarbamate (NaDDTC) was used as an analytical reagent to form the uncharged chromophore complex Cu(DDTC)2, which absorbs at 432 nm. Different physicochemical conditions (pH, temperature, reagent concentration, chemical modifiers) and hydrodynamic factors (rotation velocity, extraction time, sample volume) were optimized. Under the optimized conditions, extraction equilibrium times of 30, 53 and 90 min were obtained for 100, 500 and 1000 mL of sample, respectively, with preconcentration factors of 286, 712 and 1284, respectively. The methodology was precise (repeatability and reproducibility of 7.2 and 8.4%, respectively, as relative sta