Based on the reaction of Zn(II), thiocyanate and 2-[2-(5-dimethylamino-thiophen-2-yl)-vinyl]-1,3,3-trimethyl-3H-indolium bromide (DTVTI), a donor-active solvent-assisted liquid-phase microextraction procedure followed by spectrophotometric determination of zinc at 570 nm was developed. The optimum experimental conditions were investigated and found to be as follows: concentration of NH4SCN 0.02 mol L-1, concentration of DTVTI 4 × 10-5 mol L-1. Various extraction solvents were studied alone as well as in mixtures with different improvers, and a mixture of toluene as the extraction solvent and tributylphosphate as the donor-active solvent in a 4:1 v/v ratio was selected. The calibration plot was linear up to 2.62 mg L-1 of zinc with limit of detection 0.09 mg L-1. The developed procedure was applied for zinc determination in dietary supplements.
zinc; donor-active solvent-assisted liquid-phase microextraction (DAS-LPME); dietary supplements; spectrophotometry
