利用谱睿(Pre)技术超大体积进样抑制型电导离子色谱法检测超纯水中ng/L级阴离子

利用谱睿(Pre)自动样品前处理技术,10 mL超大体积进样,对超纯水样品进行在线预浓缩,检测了电厂水中ng/L级的超痕量阴离子。选择的离子色谱条件为:高容量氢氧化物选择性IonPac AS18阴离子交换色谱柱,淋洗液发生装置在线产生氢氧化钾进行梯度淋洗,抑制型电导检测。该方法选用的自动在线水纯化装置CIRA可以将电导池流出的"废液"进行在线纯化,纯化后的高纯去离子水作为载体将十通阀上大定量环中的样品冲入到六通阀上的超低压浓缩柱上,最后运用阀切换技术实现进样。在提供稳定的系统空白的同时,该方法还具备自动化程度高、操作简单、重现性好、灵敏度高、系统稳定、节约时间、成本低廉等多方面特点。方法参数为:对于电厂水样品,常见阴离子的检出限(s/N=3)均低于2 ng/L,线性相关系数均大于0.999,方法精密度(RSD,n=10)为1.151%~3.347%。经中、日、韩、泰、美等多个实验室共同验证,该方法可靠实用,可以应用于火电厂和核电厂超纯水中阴离子的检测。

Determination of Trace Anions in Ultrapure Waters by Suppressed Conductivity Ion Chromatography with Pre On-line Sample Preparation Technique

An ion chromatographic method with the automatic sample pretreatment (on-line pre-concentration) technique combined with ultra-large volume sample injection (10 mL) for the determination of trace anions (ng/L level) in ultra pure waters from power plants was established. The high capacity hydroxide-selectivity IonPac AS18 anion exchange column, Eluent Generator (EG) which automatically and on-line produce gradient KOH eluent, and suppressed conductivity detector were used for the separation and detection of anions. A new on-line water purification technique and equipment, CIRA device, was introduced to ion chromatographic system, which on-line purified the "waste solution" from conductance cell. The purified high grade de-ionized water flushed the sample from large loop in ten-port valve to the low pressure concentrator in six-port valve and then the sample injections were achieved through the valve-switching technique. The new method coupled with CIRA technique can provide the advantages of stable system blank, high automation, easy operation, excellent reproducibility, high sensitivity, good stability, time saving and low cost. The detection limits of the method for anions are lower than 2 ng/L with linear coefficient of higher than 0.999 and precision of 1.151% RSD to 3.347% RSD (n=10). The method has been applied to the determination of trace anions in ultrapure waters from power plants and nuclear power plants.