Ultrasound-Assisted Ionic Liquid-Based Microextraction for Preconcentration of Arsenic Prior to its Determination by Electrothermal Atomic Absorption Spectrometry

A novel ionic liquid-based microextraction methodology was developed for preconcentration of ultra-traces of arsenic prior to its determination by electrothermal atomic absorption spectrometry (ETAAS). As(III) was extracted as ammonium pyrroldinedithiocarbamate (APDC) complex from 10 mL sample into a 50 μL-volume of ionic liquid, 1- hexyl-3-methylimidazolium hexafluorophosphate, with the aid of sonication in an ultrasonic bath. Several variables affecting microextraction efficiency and ETAAS signal were optimized. Under the optimum experimental conditions, the detection limit (3s) was 0.01 μg L-1 and the enhancement factor was 208. The relative standard deviation for six replicate determinations of 0.2 μg L-1 As(III) was 4.6 %. The method was validated by analysis of a certified reference material and applied to the determination of arsenic in water samples. The proposed procedure is effective, very simple and fast; it does not require cooling, centrifugation and other time-consuming steps.