Simultaneous determination of ultra-low traces of lead and cadmium in food and environmental samples using dispersive solid-phase extraction (DSPE) combined with ultrasound-assisted emulsification microextraction based on the solidification of floating organic drop (UAEME-SFO) followed by GFAAS

Abstract

Dispersive solid-phase extraction (DSPE) combined with ultrasound-assisted emulsification microextraction (UAEME) has been developed as a novel approach for the determination of lead and cadmium in food and environmental samples prior to graphite furnace atomic absorption spectrometry. SBA-15/CCMet was synthesized and used as a new sorbent for the extraction of metal ions in DSPE. It was characterized by TEM, and FT-IR techniques. After the DSPE step, stripped metal elements were complexed with diethyldithiophosphate (DDTP), and then the complexes were extracted into 1-undecanol using UAEME. Variables affecting the performance of both steps were thoroughly investigated and their effects on the selectivity and efficiency of the whole sample preparation process are discussed. Some parameters such as the type and volume of the extraction solvent, sonication time, pH, ionic strength and centrifugation time were evaluated and optimized. Under the optimized conditions, the limits of detection were 0.2 ng L⁻¹ for Pb²⁺ and 0.5 ng L⁻¹ for Cd²⁺, with a preconcentration factor of 1800. The optimized method exhibited a good precision level with relative standard deviation (RSD%) values of 4.8% and 5.1% for 0.1 μg L⁻¹ Pb²⁺ and Cd²⁺ respectively (n = 7). The proposed method was successfully applied to the extraction of Pb and Cd in different food and environmental samples. Application of the proposed method to the analysis of fish certified reference material produced results that were in good agreement with the certified values.