中文摘要：

应用1-（2-吡啶偶氮）-2-萘酚（简写作PAN）-镍（Ⅱ）共沉淀体系，以锰（Ⅱ）为内标，在pH9的氨性缓冲溶液中对食盐中痕量铅（Ⅱ）进行快速共沉淀富集，并用火焰原子吸收光谱法测定铅的含量，对共沉淀条件作了优选。在优化的条件下，试液中作为内标的锰（Ⅱ）及铅（Ⅲ）离子均定量地与PAN—Ni（Ⅱ）共沉淀析出。锰（Ⅱ）、铅（Ⅱ）及镍（Ⅱ）均匀地存在于沉淀中，而且在铅（Ⅱ）、锰（Ⅱ）之间或镍（Ⅱ）、锰（Ⅱ）之间存在着一定的比例关系。因此，根据共沉淀中铅（Pb1）及锰（Mn1）的吸光度APb1，AMn0，的比值即可求得铅的含量（w％），原试样中铅含量（Pb0）可由下式计算：mPb0=APb2／AMn1·mMn0。试验结果表明，经过共沉淀分离，基体干扰已予消除。此方法的检出限为3．18×10^-2mg·L。应用于3种不同来源的食盐的分析，算得铅含量测定值的RSD（n=6）均小于4．3％，回收率测得值在95．4％至101．6％之间。

英文摘要：

Trace amounts of lead in table salt were separated by co-precipitation with PAN-Ni （ Ⅱ ）, and adding Mn（ Ⅱ ） ion as internal standard. Conditions for co-precipitation were optimized. Under the optimized reaction conditions, the internal standard Mn（ Ⅱ ） and Pb（ Ⅱ ） ions in the sample were quantitatively co-precipitated by PAN-Ni（ Ⅱ ）, and both of the Mn（Ⅱ ） and Pb（Ⅱ）, also including Ni（ Ⅱ ） were present in the precipitate with good homogeneity, and a definite ratio was kept between Pb（ Ⅱ ） and Mn（ Ⅱ）, or between Ni（ Ⅱ） and Mn（ Ⅱ ）. The mass of lead in the sample was calculated from the ratio of absorbances APb1 and AMn1 of lead （Pb1） and manganese （Mn1） found in the co-precipitate. Lead content （Pb0） in the original sample was calculated by the following formula： mPb0 =Apb1/AMn1 · mMn0. It was Shown by experimental results that by the separation mentioned above, the matrix interference was effectively eliminated. Detection limit of this method was found to be 3.18×10^-2mg·L^-1. In the analysis of 3 kinds of table salt by this method. RSD＇s （n=6） obtained were less than 4. 3%, and recoveries in the range of 95. 4%-101.6% were found.