Determination of Lead and Cadmium in Litchi and Longan Samples by Cloud Point Extraction Coupled with Thermospray Flame Furnace Atomic Absorption Spectrometry

A sensitive method based on cloud point extraction(CPE) coupled with thermospray flame furnace atomic absorption spectrometry(TS-FF-AAS) was proposed for the determination of trace lead and cadmium in litchi and longan samples.Factors affecting the cloud point extraction of lead and cadmium,such as sodium diethyldithiocarbamate(DDTC) concentration,pH,TritonX-100 concentration,extraction time and interference ions were investigated.Results indicated that the optimal extraction parameters were pH 5.0,extraction temperature of 100 ℃,extraction time of 15 min,Triton X-100 concentration of 0.3%,DDTC concentration of 0.02 g/100 mL and sample flow rate of 0.3 mL/min.Under the optimal conditions,Pb and Cd were enriched by 30 folds and 26 folds,respectively.The limits of detection of Pb and Cd were 2 ng/mL and 0.1 ng/mL,and the relative standard deviations(RSDs) were 5.2% and 3.6%,respectively.The proposed method was successfully applied to the determination of lead and cadmium in litchi and longan samples.