离子色谱法同时测定北京市不同区域水体6种阳离子

Ion chromatography for simultaneously determining six cations in water bodies of different areasof Beijing

建立离子色谱法测定不同区域水体Li^(+)、Na^(+)、NH_(4)^(+)、K^(+)、Ca^(2+)、Mg^(2+)等6种阳离子的方法,以及验证方法在实际应用的可行性.以ICS1000型离子色谱仪配有DionexIonPac CG12A阳离子保护柱(4 mm×50 mm)和CS 12A阳离子分离柱(4 mm×250 mm),CSRS 300型抑制器(4 mm),甲基磺酸为淋洗液,流量为1.0 mL·min^(−1),6种阳离子的质量浓度在0.01—0.50 mg·L^(-1)到5.0—100.0mg·L^(-1)范围内线性较好,相关系数>0.9995,方法检出限为0.002—0.020 mg·L^(-1),与有证标准溶液相对误差−2.50%—4.38%(n=6),不同环境水样加标回收率90.7%—107.5%.利用以上色谱条件分析北京市不同区域地表水阳离子分布特征,结果显示城乡结合部、城区和郊区水体pH稳定,呈弱碱性;城乡结合部水体6种阳离子总浓度为150.05 mg·L^(-1),明显高于城区和郊区25.35%和63.54%,阳离子浓度均值大小为:Ca^(2+)>Na^(+)>Mg^(2+)>K^(+)>NH_(4)^(+)>Li^(+),其中Ca^(2+)和Na^(+)是3个区域水体的优势离子,NH_(4)^(+)和Li^(+)质量浓度最低;城乡结合部和城区水体阳离子浓度在夏季和秋季低于春季和冬季.实验结果表明,离子色谱法样品处理简便,分析速度快,准确可靠,灵敏度高,重复性好,适用于地表水中6种水溶性阳离子的快速批量测定.

A method for determination of Li^(+),Na^(+),NH_(4)^(+),K^(+),Ca^(2+)and Mg^(2+)in different areas of water bodies by ion chromatography was established,and verify the feasibility of the method’s chromatographic conditions and characteristic indexes in the laboratory.The method precautions were also discussed for the reference of model ICS1000 chromatography with DionexIonPac CG12A cation protection column(4 mm×50 mm)and CS 12A cation separation column(4 mm×250 mm),CSRS 300 suppressed conductivity detector(4 mm),methane sulfonic acid as eluent,and flow rate of 1.0 mL·min^(−1).The mass concentration of six cations had a good linear relationship with the chromatographic peak area in the range of 0.01—0.50 mg·L^(-1)and 5.0—100.0 mg·L^(-1),correlation coefficient>0.9995,and the detection limits of the method were 0.002—0.020 mg·L^(-1),the relative error of−2.50%—4.38%(n=6)with the certified standard solution,and the recovery rate of standard addition of water samples measured in different environments was 90.7%—107.5%.Six cations in different areas of water bodies in Beijing were analyzed according to the above-mentioned chromatography conditions,and the result reflects that water bodies were weakly alkaline and pH was stable,the total concentration of six cations(150.05 mg·L^(-1))in the urban and rural joint area was higher than the city proper and the suburbs(25.35%and 63.54%);Order of mean values of cation concentrations:Ca^(2+)>Na^(+)>Mg^(2+)>K^(+)>NH_(4)^(+)>Li^(+),Ca^(2+)and Na^(+)were the dominant ions,while NH_(4)^(+)and Li^(+)had the lowest concentrations.The total concentration of six cations of the urban and rural joint area and city area in summer and autumn was lower than in spring and winter.The results showed that the method is simple sample preparation,rapid determination,high sensitivity and accuracy,good repeatability,which is suitable for rapid determination of cations in surface water.