微波消解ICP-OES法测定PM2.5中金属元素

重金属具有不可降解性，细颗粒物（PM2.5）中重金属可随呼吸进入体内，对人体构成潜在的威胁。因此，有必要针对颗粒物中重金属元素的测定方法进行研究。用玻璃纤维滤膜采样、密闭微波消解进行前处理，建立了电感耦合等离子体发射光谱仪（ICP-OES）测定PM2.5中铅、锌、铜、镉、铬的分析方法。考察了微波消解体系，通过信噪比选取了铅、锌、铜、镉、铬的最佳分析谱线和最优仪器测试条件，其结果为：（1）HNO₃-H₂O₂消解体系比HNO₃-HCl和HNO₃-H₂SO₄消解体系更稳定、更彻底;（2）铅、锌、铜、镉、铬的最佳分析线分别为220.353，213.857，327.393，228.802，267.716 nm;（3）仪器最优测试条件为射频功率1 300 W，蠕动泵流速1.5 mL·min-1，冷却气流量15 L·min-1，载气流速0.8 L·min-1。本方法元素的检出限为2.02×10-3～8.20×10-3μg·mL-1，滤膜样品测定的相对标准偏差（RSD，n=6）为1.86%～2.82%，加标回收率为91.6%～103.7%。对重庆市中科院万州监测点细颗粒物中铅、锌、铜、镉、铬的含量进行了分析，结果表明：万州城区细颗粒物没有受到镉和铬的污染，细颗粒物中铅处于潜在污染水平，锌和铜处于轻度污染水平。

Determination of Metal Elements in PM2.5 by ICP-OES with Microwave Digestion

In the present work, a method was developed for determining lead, zinc, copper, cadmium, znd chromium in PM2.5 by inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis with microwave digestion and glass fibre filter collection of samples. The microwave digestion systems were investigated and the experimental conditions were optimized. The results show that (1) HNO₃-H₂O₂ digestion system is more stable and complete than HNO₃-HCl and HNO₃-H₂SO₄ digestion systems; (2) The most sensitive emission wave length of lead, zinc, copper, cadmium, and chromium are 220.353，213.857，327.393，228.802，and 267.716 nm, respectively; (3) The highest signal-to-noise ratios were observed under the conditions: RF power of 1 300 W, peristaltic pump flow rate of 1.5 mL·min-1, cooling gas flow rate of 15 L·min-1，and carrier gas flow rate of 0.8 L·min-1. In addition, the detection limit for these elements ranged between 2.02×10-3 and 8.20×10-3 μg·mL-1, the relative standard deviations (RSD, n=6) for the samples were in the range of 1.86%～2.82%, and the recovery for the elements determined was from 91.6% to 103.7%. The proposed method was used for determination of the above five elements in atmospheric fine particulate matter at Wanzhou Monitoring Site of Chongqing Institute of Green and Intelligent Technology. The results revealed that the atmospheric fine particulate matter at this monitoring site was not polluted by cadmium and chromium, lead was at the level of potential contamination, while zinc and copper were at the level of slight pollution.