Online multichannel ultrasonic extraction for high throughput determination of arsenic in soil by sequential injection slurry hydride generation atomic fluorescence spectrometry

A new analytical method was developed to determine trace arsenic in soil by coupling sequential injection multichannel ultrasonic extraction and online pre-reduction with slurry hydride generation atomic fluorescence spectrometry. Significantly enhanced sampling throughput, reduced sample and reagent consumption, and minimized potential contamination and analyte loss were achieved. Slurry samples spiked with different concentrations of As(III) and hydrochloric acid were pumped into the ultrasonic extraction chamber for 20-minute irradiation to efficiently extract As, which were subsequently merged with a mixture of 1% (m/v) thiourea and 0.5% (m/v) ascorbic acid to pre-reduce As(V) species to As(III), followed by the generation of AsH3 via using KBH4. Upon optimization of experimental parameters, limits of detection (LODs) ranging from 30 to 70 ng g(-1) were obtained, and the precisions (RSDs) of this method were better than 2.0%. The proposed method was used for the determination of trace arsenic in several Certified Reference soil samples, with the obtained results in excellent agreement with certified values based on a simple and fast standard addition method.