在线中和富集及标准加入离子色谱法测定大气吸收液中的痕量阴离子

建立了大体积进样后的在线中和富集及在线标准加入离子色谱法,实现了对大气碱性吸收液中痕量氯离子、亚硝酸根、硝酸根、硫酸根的直接测定。比较了不同阀切换时间窗及在线中和柱的选择,确定了最佳的实验条件。利用戴安公司“谱睿”在线中和技术,通过Inguard H在线中和柱和CRD 200在线二氧化碳去除装置的共同作用,有效地去除了碱性吸收液中的OH~和CO2~3,使测定干扰降低到最小;通过大体积进样和在线富集,改进了样品的检出限,Cl~, NO~2, NO~3和SO2~4的检出限分别为17.5、171、34.7和42.4 ng/L;在线标准加入解决了痕量阴离子标准溶液的配制难题及NO~2低回收率对检测结果的影响。本方法实现了自动化分析,结果准确,重复性好,检测效率高,可用于常规离子色谱条件下无法测定的强碱性基体样品中痕量阴离子的准确测定。

Determination of trace anions in atmosphere absorption solution by ion chromatography with the application of online sample neutralization, column concentration and online standard addition

A novel ion chromatographic method was developed to directly determine trace anion (Cl(-), NO2(-), NO3(-), SO4(2-)) in atmosphere absorption solution with incorporation of large volume injection, online sample neutralization, column concentration and online standard addition. After comparing the results in different valve switching times and the chromatograms using different online neutralizing columns, the optimum experimental conditions were established. The application of Inguard H online neutralizing column and Carbonate Removal Device (CRD 200) eliminated the matrices OH(-) and carbonate. The improvement of the anion detection limit could be achieved by using large volume injection. The results showed that the detection limits of Cl(-), NO2(-), NO3(-) and SO4(2-) were 17.5, 171, 34.7, and 42.4 ng/L, respectively. Online standard addition replaced the preparation of trace anion standard solution and avoided the low recovery of NO2(-). The method has the characteristics of automatic operation, good repeatability and high efficiency, and can be applied to the detection of ultra trace anions which are hard to be determined in common ion chromatography.