超声辅助离子液体分散液相微萃取石墨炉原子吸收光谱法测定食品中铅镉

The determination of cadmium and lead in food by ultrasound assisted ionic liquid-dispersive liquid phase microextraction combined with graphite furnace atomic absorption spectrometry

建立了一种简单高效的超声辅助离子液体分散液液微萃取(UA-IL-DLLME)结合石墨炉原子吸收光谱法(GFAAS)测定食品中超痕量铅镉。以二乙基二硫代磷酸铵(DDTP)为配位剂,离子液体1-丁基-3-甲基咪唑六氟磷酸盐[C_4Mim][PF_6]为萃取剂,超声用于辅助分散离子液体和加速传质。考察优化了影响萃取效率的主要参数如离子液体的种类和体积、样品液p H、螯合剂的用量、超声时间、离心转速与时间等。在最优的萃取条件下,镉铅的校准曲线分别在0.05~20μg/L和0.5~40μg/L范围呈良好的线性,相关系数分别为0.9983 and 0.9969,检出限(S/N=3)分别为0.032和0.32μg/kg,相对标准偏差(RSD,n=11)分别为1.3%和1.8%。大米和白兰地中镉铅3个水平1.60、16.00、32.00μg/kg的平均加标回收率在95.2~102%范围。方法已成功用于检测不同食品中镉铅含量。

A simple and efficient method for the determination of Cd and Pb in food was developed by ultrasoundassisted ionic liquid dispersive liquid-liquid microextraction（UA-IL-DLLME）and graphite furnace atomic absorption spectrometry（GFAAS）detection. Ammonium diethyldithiophosphate（DDTP）was used as the complexing agent and ionic liquid（IL）1-butyl-3-methylimidazolium hexafluorophosphate [C4 Mim][PF6]was used in extracting. Ultrasound was applied to assist the dispersion of IL and accelerate the mass transfer process. Major parameters affected the extraction efficiency was investigated and optimized,which including the type and volume of ionic liquid,the p H of sample solution,amount of chelating agent,sonication time,centrifugation rate and time. Under the optimal extraction conditions,the calibration curves have a good linear over the range of 0.05 - 20 μg/L for Cd and 0.5 ~ 40 μg/L for Pb,and its correlation coefficients was 0.9983 and 0.9969 for Cd and Pb,respectively. The limits of detection were 0.032 and 0.32 μg/kg with relative standard deviations（RSD,n=11）of 1.3% and 1.8% for Cd and Pb,respectively. Recoveries of Cd and Pb at three spiked levels of 1.60、16.00、32.00 μg/kg in brandy and rice were in the range of 95.2 ~ 102%. The method has been successfully applied for the determination of cadmium and lead in different food samples.