离子色谱-柱后衍生-紫外检测法测定锅炉水汽中的微量硅

Determination of trace silica in boiler water-steam by IC-postcolumn deriviation-UV detection method

本文建立了离子色谱-柱后衍生-紫外检测法测定锅炉水汽中微量硅酸盐的方法。选用X10010μm Bischoff 250×4.0mm不锈钢色谱柱,测试条件为:以25mM NaOH+0.5mM NaHCO_(3)为淋洗液,流量为1.0mL·min^(-1),色谱柱柱温为45℃;柱后衍生剂为200mM HNO_(3)+20mM Na2MoO_(4),流量为0.35mL·min^(-1);衍生温度70℃,紫外检测波长为360nm。结果显示,方法可在13min内完成,硅酸盐在2~40μg·L^(-1)浓度范围内与色谱峰面积线性关系良好,方法检出限为0.18μg·L^(-1)。测定3种不同浓度的硅标准溶液,相对标准偏差(RSD)为1.64%~2.04%,相对误差为2.68%~4.75%。饱和蒸汽与过热蒸汽的加标回收率分别为95.3%~105.2%与93.2%~102.0%。研究表明,该方法选择性与灵敏度高,准确性好,适合于大批量电站锅炉水汽质量检验中硅酸盐的测定。

An ion chromatographic method with post-column deriviation and UV detection for the determination of trace silica in boiler water-steam was proposed.The sample was separated on ion chromatography system equipped with X10010μm Bischoff 250×4.0mm stainless steel column.25mM NaOH+0.5mM NaHCO_(3) were selected as elution solvent,with flow rate of 1.0mL·min^(-1) and the reaction temperature at 45℃.200 mmol·L^(-1) nitric acid+20mmol·L^(-1) sodium molybdate were used as postcolumn derivatization reagent,with flow rate of 0.35mL·min^(-1) and the reaction temperature fixed at 70℃.The ultraviolet detector wavelength was set at 360nm.The results showed that the analysis was complished in 13 minutes,and the linearity of silica was good in the mass concentration range of 2~40μg·L^(-1),with the detection limit was as low as 0.18μg·L^(-1).The relative standard deviation(RSD)values and relative error(RE)of the three different concentrations of silica standard solutions were severally 1.64%~2.04%and 2.68%~4.75%.The average recovery rate of standard addition for saturated vapor and superheated steam were 95.3%~105.2%and 93.2%~102.0%,respectively.The method has high selectivity,sensitivity and good accuracy,which is especially suitable for the determination of silica in large quantities of boiler water-steam.