浊点萃取-热喷雾火焰炉原子吸收光谱法测定荔枝和桂圆肉中痕量Pb和Cd

摘要

为测定荔枝和桂圆肉中的Pb和Cd。采用浊点萃取-热喷雾火焰炉原子吸收光谱法对该样品进行分析,考查二乙基二硫代氨基甲酸钠（DDTC）浓度、溶液pH值、TritonX-100浓度、加热时间、水浴温度、干扰离子等实验条件对浊点萃取效率的影响。在最优试验条件下,即pH5.0、温度100℃、萃取时间15min、TritonX-100体积分数0.3%、DDTC质量浓度0.02g/100mL、进样速率0.3mL/min,该方法对Pb和Cd的富集倍数分别为30倍和26倍;方法的检出限对Pb和Cd分别为2ng/mL和0.1ng/mL,相对标准偏差分别为5.2%和3.6%。利用该方法对荔枝和桂圆中的铅和镉进行测定,结果令人满意。%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.