活性炭富集-电热塞曼原子吸收光谱法测定水中痕量的汞

Activated Carbon Enrichment Combined with Pyrolysis Zeeman Atomic Absorption Spectroscopy for Determination of Trace Amounts of Mercury in Water

建立了一种水中痕量汞的测定方法。通过活性炭定量吸附水中痕量汞,采用电热塞曼原子吸收光谱法测定活性炭富集的汞。与目前水中总汞测定方法相比,本方法避免了消解等步骤,减少了汞污染和汞损失,操作更加简单。考察了活性炭粒度、酸处理方法、酸介质和富集时间对富集效率的影响,以及热解温度和干扰离子对方法测定结果的影响。通过空白活性炭加标、空白溶液加标和环境水样加标3种方法制作标准曲线,三者的相关系数达0.9999,经统计检验,3条标准曲线的斜率无差异,表明了在此实验条件下环境水样中的共存物不干扰汞的测定,同时也表明可直接用空白活性炭加标的方法进行标准曲线的绘制。采用本方法对含5和50 ng/L汞的水样进行测定,其相对标准偏差分别为7.2%和4.2%（n=11）。本方法测定下限达到1.2 ng/L。地表水和自来水样中添加10 ng/L汞的加标回收率在92.0%-103.0%之间。用 ICP-MS作对照,二者分析结果相符合,相对误差在2.9%- 3.4%之间,表明本方法准确可靠、精密度好。

Abstract A method for determination of trace mercury in water was established. The trace mercury in water was adsorbed quantitatively by activated carbon, and then determined by electrical pyrolysis atomic absorption spectrometry. In comparison with the detection methods of total mercury in water at present, the method avoids the steps of digestion, reduces the mercury pollution and the loss of the mercury, and is simple in operation. The effects of particle size of activated carbon, acid treatment method, acid medium and enrichment time on the enrichment efficiency were investigated. The effect of the pyrolysis temperature and the interfering ions on the determination results was investigated. Three standard addition procedures including activated carbon blank addition, solution blank addition and environmental water samples addition were studied. Regression correlation coefficients of three standard curves drawn by the three methods reached 0 . 9999 . The slope of the three standard curves had no difference by statistical test, indicating that the determination of mercury in environmental water samples under the experiment conditions was not interfered by the coexistent elements, which showed that the activated carbon blank addition method could be directly used for preparing standard curve of the method. The water samples containing 5 ng/L and 50 ng/L mercury were determined by the method, and the relative standard deviation were 7. 2% and 4. 2% （n=11）, respectively, with a detection limit of 1. 2 ng/L. The recovery experiment was carried out after adding 10 ng/L mercury to the surface water and tap water samples, and the recoveries were between 92. 0% and 103. 0%. Analysis results were compared with ICP-MS as control and the deviation of the two methods were between 2 . 9% and 3 . 4%, indicating that the method was accurate and reliable, and had good precision.