Simultaneous pre-concentration of Pb and Sn in food samples and determination by atomic absorption spectrometry

A cloud point extraction (CPE) method has been developed for the pre-concentration and simultaneous determination of lead [Pb(II)] and tin [Sn(II)] using Acridine Orange as complexing reagent and mediated by nonionic surfactant (Triton X-114) by flame atomic absorption spectrometry (FAAS). The main factors affecting analytical performance of CPE have been investigated in detail. The extracted surfactant-rich phase was diluted with (1.0 mol L-1) nitric acid in methanol, prior to subjecting FAAS. The calibration graphs obtained from Pb(II) and Sn(II) were linear in the concentration ranges of 5-1,000 and 10-5,000 mu g L-1 with detection limits of 1.40 and 2.86 mu g L-1, respectively. The relative standard deviations for 10 replicates containing 25 mu g L-1 of Pb(II) and Sn(II) were 2.15 and 2.50 %, respectively. The analytical procedure was verified by the analysis of the standard reference materials NWTMDA-61.2 (water-trace elements) and NIST SRM 1548a (typical diet). The developed method has been applied to the simultaneous determination of total Pb and Sn in canned food samples including juices, tomato paste, corn, and green pea.