Dispersive Solid-phase Microextraction of Lead in Waters and Edible Lettuce and Dill Extracts in the Unified Bioaccessibility Method (UBM) Saliva Solution.

A new thiosemicarbazide-modified, sulfonamide-based poly (styrene) adsorbent (T-CSPS) was prepared starting from the reaction of chlorosulfonated polystyrene and thiosemicarbazide. It was characterized by SEM-EDX, FT-IR, and zeta potential. The T-CSPS was used as an adsorbent for the first time for the dispersive solid-phase microextraction (d-SPµE) and preconcentration of Pb(II) ions from waters and dill and lettuce extracts in the unified bioaccessibility method (UBM) saliva. Lead was then determined using the FAAS. In the first step of optimization, the solution pH was changed from 2 to 8, and pH 4 with a recovery value of 103% ± 5 was selected. Two milliliters of 2 mol L HCl was chosen as eluent. Contact times were found to be only 2 min. Effects of coexisting ions and sample volume were tested. Under optimal conditions, the preconcentration factor (PF) and the adsorption capacity were 15 and 40 mg g. The RSD% was 2.2% and 3.1% for intra-day and inter-day precision, respectively. The LOD and LOQ were found to be 5.1 µg L and 16.9 µg L, respectively. The accuracy of the d-SPµE was checked by TMDA-70.2 Lake water and BCR-482 Lichen-certified reference materials and also applying d-SPµE to spiked waters and lettuce and dill extracts in UBM saliva.