Selective Extraction and Determination of Arsenic (III) and Arsenic (V) in Some Food Samples by Cloud-Point Extraction Coupled with Hydride Generation Atomic Absorption Spectrometry

Aims: To develop a new selective approach for the extraction and determination of trace amounts of As(III) and As(V) in some food samples by cloud point extraction (CPE) using two new synthesized ligands coupled with hydride-generation atomic absorption spectrometry (HG-AAS).

Study Design: All significant variables for both As (III) and As (V) species that impact the separation and determination steps were studied by one factor-at-a-time (OFAT) optimization.

Place and Duration of Study: Department of Chemistry, College of Science for Women, University of Baghdad, Baghdad, Iraq between October 2012 and May 2013.

Methodology: The method involved the selective complexation of As (III) with 7-(6-BrBTA8HQ) or As (V) with 7-(6-MBTA8HQ) at certain pH values. Then the two complexes were individually extracted into a non-ionic surfactant (Triton X-114) and separated by centrifugation from which the two species were individually determined by means of HG-AAS. The established method was applied to the determination of the two As species in the fish and honey samples with satisfactory results where the detection limits of the method in the sample were of 0.0033 and 0.0065 µg g-1 for As (III); 0.0063 and 0.0125 µg g-1 or As(V) in fish and honey samples respectively.

Results: Under the optimum established conditions, the enrichment factors of 80 and 73.7 fold were obtained for As (III) and As (V) respectively leading to detection limits of 1.3 ng mL-1 of As(III) and 2.5 ng mL-1 for As(V) in aqueous solution. The Beer’s law was obeyed in concentration range of 1.5-100 ng mL-1 for As (III) and 4-150 ng mL-1 for As (V). The accuracy of the method was checked by the standard additions procedure. The percent recoveries of As (III) and As (V) were found to be in the range of 98.3-99.3% and 98-101.6% respectively.

Conclusion: The establish method avoids the steps of oxidation/reduction of As species giving good analytical figures of merit and being most suitable for the determination of two As species individually in the selected samples and other food matrices.