大气PM2.5中25种元素的电感耦合等离子体质谱法定量分析及其酸溶性差异

Determination of 25 elements in ambient PM2.5 by ICP-MS and analysis of acid soluble and insoluble content

目的建立PM2.5中25种元素含量的电感耦合等离子体质谱(ICP-MS)测定法,应用该法测定PM2.5中25种元素含量并分析其酸可溶性与不溶性含量。方法采用石英滤膜采集大气样品,样品剪碎后分别经微波消解与5%硝酸超声提取,用ICP-MS法测定滤膜中25种元素含量,并用配对t检验比较超声提取与微波消解两种前处理检测结果的差异。结果在PM2.5采样滤膜中加入5μg/L和50μg/L混合标准溶液后,得到各元素的相对标准偏差分别为0.1%~3.8%和0.2%~1.6%,内标回收率在85%~115%之间,线性关系良好(r>0.999 5),方法检出限为0.000 75~0.64μg/g。样品经微波消解处理后的Al、Mg、Cd、Co、Cr、Cu、Fe、Ni、Sb、Se、Sn、Ti和Tl 13种元素测定结果高于经超声提取后的测定结果,Zn则相反,差异均有统计学意义(P<0.05);Be、Ca、Ba、Sr、K、V、Mn、As、Ag、Hg和Pb 11种元素经两种前处理方法的检测结果差异无统计学意义(P>0.05)。经超声提取前处理测定的25种元素占采样总量的(4.00±0.40)%,经微波消解前处理测定的25种元素占采样总量的(5.12±0.42)%,前者低于后者,差异有统计学意义(P<0.05)。结论该方法灵敏度高,准确度好,检出限低,线性相关良好,样品用量少,高效快速。本次采集的大气PM2.5成分中,25种元素中可溶性元素占采样总量的4.00%,不溶性元素占采样总量的1.12%。

Objective To establish an ICP-MS method for the determination of 25 elements in ambient PM2.5.The contents of 25 elements in PM2.5 were determined by ICP-MS and the acid soluble and insoluble contents were analyzed.Methods The air samples were collected by quartz filter membrane.The samples were respectively prepared by microwave digestion system and 5%nitric acid ultrasound.The contents of 25 elements in the filter membrane were determined by ICP-MS method.The differences of the results between the two pretreatment methods of ultrasonic extraction and microwave digestion were compared based on paired t-test.Results The 5μg/L and 50μg/L mixed standard solutions were continuously measured six times,and the RSDs of each element was 0.1%-3.8%and 0.2%-1.6%,the recoveries of internal standard were 85%-115%,the correlation coefficient r>0.999 5 was found in the standard curve,and the limits of detection were 0.000 75-0.64μg/g.There were significant differences in the results of Al,Mg,Cd,Co,Cr,Cu,Fe,Ni,Sb,Se,Sn,Ti,Tl and Zn based on pretreatment methods(P<0.05);There were no significant differences in the results of the two pretreatment methods for Be,Ca,Ba,Sr,K,V,Mn,As,Ag,Hg and Pb(P>0.05).The proportion of 25 elements in PM2.5 was(4.00±0.40)%by ultrasonic extraction and(5.12±0.42)%by microwave digestion(n=6).The difference between the two results was statistically significant(P<0.05).Conclusion The method for the determination of 25 elements in filter membranes by ultrasonic extraction and microwave digestion-ICP-MS has been established,and it has the advantages of high sensitivity,good accuracy,low detection limit,good linear correlation,less sample consumption,high efficiency and rapidity.A total of 25 elements in ambient PM2.5 in Lianyungang in March accounted for 4.00%of the total sample,insoluble elements accounted for 1.12%of the total sample.