Development of an inexpensive and sensitive method for the determination of low quantity of arsenic species in water samples by CPE-FAAS

The simple and rapid preconcentration technique using cloud point extraction (CPE) was applied for the determination of As(V) and total inorganic arsenic (As(V) plus As(III)) in water samples by means of FAAS. As(V) has formed an ion-pairing complex with Pyronine B in the presence of cetyl pyridinium chloride (CPC) at pH 8.0 and extracted into the non-ionic surfactant Triton X-114, after centrifugation the surfactant-rich phase was separated and diluted with 1.0 mol L⁻¹ HNO₃ in methanol. The proposed method is very versatile and economic because it exclusively used conventional FAAS. After optimization of the CPE conditions, a preconcentration factor of 120, the detection and quantification limits of 1.67 and 5.06 μg L⁻¹ with a correlation coefficient of 0.9978 were obtained from the calibration curve constructed in the range of 5.0-2200 μg L⁻¹. The relative standard deviation, RSD as a measure of precision was less than 4.1% and the recoveries were in the range of 98.2-102.4%, 97.4-101.2% and 97.8-101.1% for As(V), As(III) and total As, respectively. The method was validated by the analysis of standard reference materials, TMDA-53.3 and NIST 1643e and applied to the determination of As(III) and As(V) in some real samples including natural drinking water and tap water samples with satisfactory results. The results obtained (34.70 ± 1.08 μg L⁻¹ and 60.25 ± 1.07 μg L⁻¹) were in good agreement with the certified values (34.20 ± 1.38 μg L⁻¹ and 60.45 ± 1.78 μg L⁻¹).