Ultrasound assisted-cloud point extraction combined with flame atomic absorption spectrometry for selective preconcentration and determination of As(v) in selected water and beverage samples

Abstract

In the present study, to evaluate the inorganic arsenic species at μg L⁻¹ levels, a simple and low-cost analytical method has been developed using flame atomic absorption spectrometry (FAAS). The ultrasound-assisted cloud point extraction (UA-CPE) was efficiently used to separate and preconcentrate As(V) in the presence of excess As(III) in different samples of water and beverages. The selective ion-association complex and/or π-stacking complex of As(V) with 3-amino-7-dimethylamino-2-methylphenazine (Neutral red, NRH⁺ or NR) in the presence of pyrogallol at pH 8.0 were extracted into the surfactant-rich phase of polyethyleneglycolmono-p-nonyphenylether (PONPE 7.5) from the sample matrix. After optimization of the UA-CPE conditions, the limits of detection and quantification (LOD and LOQ) obtained for As(V) with a sensitivity enhancement factor of 47.3 in the linear range of 1.5–170 μg L⁻¹ were 0.45 and 1.5 μg L⁻¹, respectively. The relative standard deviation (RSD) as a measure of precision was found in the range of 2.7–4.2%. The proposed method was successfully applied to the determination of As(V) and total As in selected water and beverage samples after rapid and efficient ultrasonic- and microwave-assisted extraction approaches before and after pre-oxidation with KMnO₄ in acidic media. The concentration of As(III) was calculated from the difference between total As and As(V) concentrations. The accuracy was validated by analysis of two certified standard reference materials (SRMs) including recovery rates of spiked samples.