阀切换-离子色谱法测定分析纯硫酸钠中痕量氯离子

Determination of trace chloride in sodium sulfate of analytical reagent-grade by valve-switching ion chromatography

建立了阀切换-离子色谱法测定分析纯硫酸钠固体中痕量氯离子含量的方法。ICS-2100离子色谱系统,配置十通阀,用IonPac AS18色谱柱将硫酸钠固体样品中的氯离子和硫酸根离子预分离后,以IonPac TAC-ULP1为富集柱,将氯离子富集后在相同的IonPac AS18色谱柱上进行定量分析。同时以淋洗液发生器产生的不同浓度的KOH作为淋洗液,以抑制型电导检测器测定氯离子的含量。结果表明,阀切换-离子色谱法测定分析纯硫酸钠固体中的痕量氯离子,检出限为10μg/L,线性相关系数(r2)大于0.999,实际样品的加标回收率为98.0%～103.0%,具有分离度和灵敏度高,选择性好,操作简单等特点。该方法能够准确测定硫酸钠固体中痕量氯离子的含量,适用于高纯化学试剂中痕量氯离子的分离测定。

A valve-switching ion chromatography system was developed for the determination of trace chloride in sodium sulfate using a single pump, a suppressor, two valves and three col- umns. Using this technique, the trace chloride was eluted from the concentrator column （ Ion- Pac TAC-ULP1, 23 mm ×5 mm） to the analytical column （IonPac ASIS, 250 mm×4 mm）, and the sulfate flowed to the waste. Under the optimized separation conditions, the method showed good linearity （ r2 〉 0. 999） in the range of 0.03 - 1 mg/L and the average recoveries of chloride were 98.0% - 103.0% with the relative standard deviation less than 2%. The limit of detection was 0.01 mg/L （S/N = 3）. The results demonstrated that this system has the advantages of high sensitivity, facile automation and simple sample pretreatment, which might be a promising approach for the determination of trace chloride in high-purity reagents.