Vortex-assisted supramolecular solvent microextraction based on solidification of floating drop for preconcentration and speciation of inorganic arsenic species in water samples by molybdenum blue method

Abstract

A new vortex-assisted supramolecular solvent microextraction based on solidification of floating drop (VA-SSM-SFD) has been developed for preconsentration and spectrophotometric determination of inorganic arsenic (iAs) species in various water samples. The method is based on the formation of arsenomolybdenium blue complex followed by VA-SSM-SFD procedure and subsequent spectrophotometric determination in a microcell. The supramolecular solvents consisted of reverse micelles of 1-dodecanol in tetrahydrofuran (THF) which were formed by in-situ coacervation of 1-dodecanol micelles in aqueous samples. Under optimized conditions, iAs (V) formed hetroploy blue complex and was directly determined. The concentration of iAs (III) was determined by subtracting iAs (III) from the total iAs following the oxidation of iAs (III) to iAs (V) by permanganate in acidic medium. Under optimal conditions, the calibration curve for iAs determination showed good linearity in the range of 5.0–140.0 μg L−1(R2 = 0.9988) and detection limit was found to be 0.4 μg L−1, which is much lower than WHO guideline of 10 μg L−1 for iAs in drinking water. The repeatability and reproducibility for 20 μg L−1 were found to be 2.47 and 3.9%, respectively. The proposed method was successfully applied to speciation of iAs species in real water samples.