固相萃取柱脱盐-石墨炉原子吸收法测定酱油中铅

Desalting with solid phase extraction cartridge and using GF-AAS for the determination of lead in soy sauce

目的建立固相萃取柱脱盐-石墨炉原子吸收法测定酱油中铅的方法。方法酱油经微波消解后,消解液用乙酸铵调节至pH≈5.5,过经用5 ml 1 mol/L乙酸铵活化后的DigiSEP-Blue柱,将被测元素铅吸附与基体中高盐分离,再分别用8 ml 2 mol/L硝酸、2 ml纯水洗脱,应用石墨炉原子吸收法测定洗脱液中铅含量。结果用固相萃取柱可将酱油中98%以上的钠盐与被测元素铅分离,消除了石墨炉原子吸收分光光度计测定铅时的基体干扰。低、高两个铅浓度(10和30 ng/ml)的加标平均回收率(n=7)分别为91.3%～95.1%,97.9%～98.6%,相对标准偏差为2.1%～7.0%,检出限为1.33 ng/g。结论方法准确、灵敏度高,适于高盐样品酱油中铅含量的测定。

Objective To establish a solid phase extraction（SPE） with atom absorption spectrometry（AAS） for the determination of lead in soy sauce samples.Methods The samples were pretreated by microwave digestion.After the digested solution being adjusted to pH 5.5 by ammonium acetate,the solution was then passed through a DigiSEP-Blue cartridge pretreated by 5 ml of 1 mol/L ammonium acetate for the removal of large amount of salt.The eluate from the DigiSEP-Blue cartridge washed by 8ml of 2 mol/L nitric acid and 2 ml of water was directly used for the analysis of lead on AAS.Results More than 98% of salt in soy sauce samples could be separated with lead by DigiSEP-Blue cartridge.The recoveries（n=7） of lead in two different samples spiked with 10 and 30 ng/ml of lead were 91.3%-95.1% and 97.9%-98.6%,respectively.The relative standard deviations（RSD） were lower than 7.0 %.The limit of detection was 1.33 ng/g.Conclusion The method was accurate and sensitive,suitable for the accurate determination of lead in soy sauce with high levels of salt.