浊点萃取-石墨炉原子吸收法测定高盐样品中的痕量铅

在pH 6～7的缓冲体系中，样品溶液中的痕量铅与加入的吡咯烷二硫代氨基甲酸铵(APDC)为络合剂形成稳定的配合物。通过70 ℃恒温水浴3 h，铅配合物被萃取到表面活性剂相并与水相分开。 分离后的表面活性剂相室温就可配成上机待测样液。 此法不但将大量基体离弃在水相，从而消除高盐带来的高背景信号干扰，并将水样或1%食盐溶液的痕量铅富集10～100倍。用氘灯校正背景石墨炉原子吸收法进行测定，方法检出限：食盐0.000 5 μg·g-1,水样0.01 μg·L-1。回收率为92.3%～104%。用于食盐、海水、井水中痕量铅的测定，结果令人满意。

Determination of Trace Lead in Water Samples and Salt Samples by Graphite Furnace Atomic Absorption Spectrometry after Cloud Point Extraction

A method was developed for the determination of trace lead in water samples and salt samples by GFAAS after cloud point extraction. The parameters of extraction system such as pH, the concentrations of the extractant and the surfactant, and the time for cloud point extraction were optimized. Under the optimized conditions, the detection limits of lead were 0.000 5 microg x g(-1) for salt, and 0.01 microg x L(-1) for water, respectively. The proposed method was applied to the determination of lead in water samples and salt samples, and satisfactory results were obtained.