环境空气PM_(2.5)中铵离子含量的两种检测方法比较

Comparison of two detection methods for ammonium ions content in ambient air PM_(2.5)

目的比较离子色谱法与流动注射分析法测定环境空气PM_(2.5)中铵离子含量。采集环境空气颗粒物PM_(2.5)的石英滤膜,各取1/4剪碎后经超纯水超声提取,离心过滤,分别用流动注射法和离子色谱法测定PM_(2.5)中铵离子的含量。结果离子色谱法测定NH_(4)^(+)在0.5~10.0 mg/L范围内拟合曲线为y=0.0710+0.2214x-0.0058x^(2),r=0.9997,检出限0.017μg/m^(3),定量限0.068μg/m^(3),回收率91.0%~96.6%,RSD 0.05%~0.08%(n=6);流动注射法测定NH_(4)^(+)在0.02~1.00 mg/L范围内线性关系良好,y=22.576x+0.1333,r=0.9999,检出限0.003μg/m^(3),定量限0.012μg/m^(3),加标回收率为105%~114%,RSD在0.54%~2.06%(n=6)之间。利用两种方法同时测定16份滤膜样本,测定结果差异无统计学意义(t=1.080,P>0.05)。结论两种方法均具有良好的线性关系、精密度及准确度,流动注射分析法与离子色谱法相比有检出限低,检测时间短等优势。

Objective Comparison of two methods for determining ammonium ion content in ambient air PM_(2.5).Methods 1/4 of the quartz filter membrane used to collect ambient air particles PM_(2.5)was cut into pieces,and ultrasound extracted by ultra-pure water,then centrifuged and filtered,and last the content of ammonium ion in PM_(2.5)was respectively determined by flow injection method and ion chromatography.Result The fitting curve of NH_(4)^(+)measured by ion chromatography in the range of 0.5~10.0 mg/L is y=0.0710+0.2214x-0.0058x^(2),r=0.9997.The detection limit of NH_(4)^(+)in PM_(2.5)is calculated to be 0.017μg/m^(3),with a quantification limit of 0.068μg/m^(3),the recovery rate is between 91.0%~96.6%,and the RSD is 0.05%~0.08%(n=6).The linear relationship of ammonium ion concentration measured by flow injection analysis in the range of 0.02~1.00 mg/L is good,with y=22.576x+0.1333,r=0.9999.The detection limit is 0.003μg/m^(3),and the quantification limit is 0.012μg/m^(3)with the recovery rate of 105%~114%and the RSD between 0.54%~2.06%(n=6).Using the two methods to measure 16 filter membrane samples,there was no statistically significant difference in the measurement results(t=1.080,P>0.05).Conclusion Both of the two methods have a good linear relationship,with good precision and accuracy.Compared with ion chromatography,flow injection analysis has the advantages of lower detection limit and shorter detection time.