离子色谱-电感耦合等离子体质谱联用测定大气颗粒物PM_(2.5)和PM_(10)中的六价铬

Determination of hexavalent chromium in atmospheric particles PM_(2.5) and PM_(10) by ion chromatography with inductively coupled plasma mass spectrometry

建立了大气颗粒物PM2.5、PM10中六价铬（Cr（Ⅵ））的离子色谱-电感耦合等离子体质谱（IC-ICP-MS）检测方法。采用碳酸氢钠（NaHCO3）溶液超声提取大气颗粒物样品中的Cr（Ⅵ）,并使用含有0.22 g/L乙二胺四乙酸二钠盐（Na2EDTA）的75 mmol/L硝酸铵溶液（pH7.0）淋洗液通过离子色谱柱（AG7,50 mm×4 mm）分离出样品中的Cr（Ⅵ）,电感耦合等离子体质谱测定。标准溶液中Cr（Ⅵ）的质量浓度在0.05-5μg/L范围内呈良好的线性关系,相关系数达0.999 9,标准溶液测定的精密度为1.0%-4.0%,标准样品测定的相对误差为3.3%;纤维素滤膜适用于Cr（Ⅵ）的采样,将纤维素滤膜碱化后,Cr（Ⅵ）的回收率从75%增加到102%;样品在20 mmol/L碳酸氢钠溶液中超声30 min后上机测试,提取完全且回收率稳定;当采样体积为20 m3,方法的检出限为0.000 4 ng/m3;采集并测定了PM2.5及PM10实际样品,样品的加标回收率为91.6%-102%,精密度为1.7%-7.6%。该方法高效、稳定、灵敏,适用于大气颗粒物中六价铬的测定。

An analytical method using ion chromatography with inductively coupled plasma mass spectrometry （IC-ICP-MS） for the determination of hexavalent chromium （ Cr （ Ⅵ ） ） in atmospheric particles PM2.5 and PM10 was established. The Cr（ Ⅵ ） in the atmospheric particles was extracted ultrasonically with sodium bicarbonate solution. An anion exchange column （AG7, 50 mm × 4 mm ） with 75 mmol/L ammonium nitrate solution （containing 0.22 g/L Na,EDTA, pH 7.0） as mobile phase was used for the separation. ICP-MS was used as a detector for the determination of hexavalent chromium. The calibration curve was linear in the range of 0.05-5 μg/L and the correlation coefficient was 0. 999 9 for Cr（ Ⅵ ）. The cellulose filter was fit for sampling. With the alkaline cellulose filter, the recovery of Cr（ Ⅵ ） increased front 75% to 102%. The recovery was complete and stable when the samples were sonicated in 20 mmol/L sodium bicarbonate solution for 30 rain. The limit of quantification （LOQ） of Cr （ Ⅵ ） was 0. 000 4 ng/m^3 when the sampling volume was 20 m^3. The average recoveries of Cr（ Ⅵ ） in the spiked PM2.5 and PM10 samples ranged from 91.5% to 102% with the relative standard deviations not more than 7.6%. The method is efficient and reliable. It can meet the requirement for the determination of Cr（ Ⅵ ） in atmospheric particles.