热解析富集-能量色散X射线荧光光谱法对溶液中汞的测定

搭建热解析富集装置对溶液中的汞富集后进行检测，可以提高X射线荧光测试的灵敏度。整个测试过程如下：样品中的汞在高温下发生热解析，经过滤膜时被选择性吸附，在使用光谱仪测试后，最终计算出样品中汞的含量。在热解析管路中加入白云石增加停留时间，可以降低汞的热解还原温度，在使用汞稳定化剂的条件下，只需加热到600 ℃就可以实现汞的解析。对热解析富集的测试条件进行研究，选择热解析时间和光谱仪器测试时间，优化进样体积和抽气气流流速。该方法的测试信号与直接测试相比明显增大，且随着样品体积的增加而增加，在进样体积为200 μL时可达到11.78倍。使用不同浓度的溶液绘制工作曲线，线性相关系数为0.993 7，并对含量为0.05 μg·mL-1的溶液进行多次测试，11次测试的相对标准偏差为4.048%；对空白溶液进行测试，计算该方法的检出限为0.004 μg·mL-1，定量限为0.015 μg·mL-1；配制混合溶液，研究其他离子对待测离子的干扰，结果表明，在其他离子含量是待测离子100倍的条件下，对汞的测试没有影响；采集生活中的河流水和自来水，测试该方法的加标回收率在94.3%～102.6%之间。使用该装置对溶液中的汞富集后进行测试，可以提高X射线荧光测试的检出限，实现污水中重金属汞的检测。

The Detection of Mercury in Solutions After Thermal Desorption-Enrichment by Energy Dispersive X-Ray Fluorescence

After designing a thermal desorption-enrichment device, the mercury in the solution could be enriched, and the sensitivity could be improved when tested by X-ray fluorescence. The test process was as follows: mercury would be desorbed at high temperature and then adsorbed selectively into the filter membrane when passing through it. After that, the membrane was tested with a spectrometer to calculate the concentration of mercury in sample finally. The thermal reduction temperature of mercury can be lowered by increasing the residence time by adding dolomite into the thermal pipeline, and in the presence of a mercury stabilizer, the desorption can be realized by heating to 600 ℃. At the same time, the test conditions of the thermal desorption-enrichment were studied, the thermal-desorption time and the test time for the spectral instrument were chosen, the injection volume and the gas flow rate of pumping were optimized. The signal amplified apparently for this method compared with testing directly and increased with the increase of sample volume, which was 11.78 times higher when the injection volume was 200 μL. Different mercury concentrations were used to draw the calibration curves, and the linear correlation coefficient was 0.993 7. A solution was tested 11 times with 0.05 μg·mL-1 and the relative standard deviation was 4.048%. When a blank solution was tested, the detection limit and quantification limit were calculated as 0.004 μg·mL-1 concentration and 0.015 μg·mL-1 respectively. Mixed solutions were prepared to study the interferences of other ions. The results showed that mercury would not be affected by other ions even when their concentrations were up to 100 times. The river water and tap water were collected, and the standard recovery rate of this method was tested, which was between 94.3% and 102.6%. The device can improve the detection limit for X-ray fluorescence and detect mercury in sewage.