Ultrasound-assisted supramolecular solvent microextraction coupled with graphite furnace atomic absorption spectrometry for speciation analysis of inorganic arsenic

Abstract

A novel ultrasonic-assisted supramolecular solvent microextraction (USASS-ME) method was proposed for the selective microextraction of As(III, V) prior to its determination via graphite furnace atomic absorption spectrometry. Supramolecular solvent (SUPRAS) was prepared from the solution of reverse micelles of decanoic acid (DeA) in tetrahydrofuran (THF) that was immediately injected into water, where water acted as the coacervating agent. Then, As(III) was complexed with ammonium pyrrolidinedithiocarbamate (APDC) and directly extracted by reverse micelle coacervates. Sonication increased the speed of homogenization and mass transfer of the target analyte into the SUPRAS. The effects of the above mentioned parameters on the recovery of As(III) were investigated. Total inorganic As(III, V) was similarly extracted after the reduction of As(V) to As(III) with the mixture of potassium iodide and sodium thiosulfate, and As(V) concentration was calculated by the difference. Under the optimized conditions, the proposed method was validated with satisfactory results. Good linearity with the coefficient of determination greater than 0.99 was obtained. The limit of detection and quantification was 0.2 and 0.7 ng mL⁻¹. Intra-day (n = 3) and inter-day (n = 3) relative standard deviations were 3.8% and 6.9%, respectively, and the enrichment factor was equal to 60-fold. The method was also successfully applied to the speciation of As in different environmental water samples and soil.