离子色谱法同时测定脱硫海水中的SO_4^(2-)和SO_3^(2-)

Simultaneous Determination of Sulfate and Sulfite in Seawater by Ion Chromatography

采用离子交换色谱法同时定量分析脱硫海水中SO_4^(2-)和SO_3^(2-)。0.01 mol/L EDTA和0.10×10^(-3) mol/L NaOH混合溶液用于除去海水样品中Ca^(2+)、Mg^(2+)干扰,加入0.5%的甲醛溶液防止SO_3^(2-)氧化为SO_4^(2-)。实验采用DINOEX AS-9HC阴离子交换柱作分离柱,以9.00×10^(-3) mol/L Na_2CO_3溶液为淋洗液,电导检测器检测。方法线性范围为5.00~100.00 mg/L,加标回收率为97.85%~103.99%,相对标准偏差(RSD)为0.20%~2.07%。SO_3^(2-)的检出限为0.03mg/L,SO_4^(2-)的检出限为0.04mg/L。结果表明,本方法可以有效消除海水中Ca^(2+)、Mg^(2+)对低浓度SO_3^(2-)、SO_4^(2-)测定的干扰,可同时实现海水脱硫体系中SO_3^(2-)、SO_4^(2-)的定量分析。

A method has been established for simultaneous determination of sulfate and sulfite with high concentration of calcium and magnesium ions in seawater by ion chromatography. To avoid anion oxidation and cation interference,0.5% formaldehyde,0.01 mol/L EDTA and 0.10× 10^-3 mol/L NaOH were chosen for antioxidant treatment and cation fixation. Separation and quantitative analysis were achieved on IonPac AS9-HC and AG9-HC column with 9.00×10^-3 mol/L NazCO3 solution as eluent at the flow rate of 1. 2 mL/min. The relative standard deviations were 0. 20%-2. 07% with average recoveries of 97. 85%-103. 99% in the range of ion concentration of 5. 00-100. 00 mg/L. The limit detections for SO^2- and SO4^2- were 0.03 mg/L and 0.04 mg/L,respectively. This method can eliminate the interference of the main cations effectively and be applied for the determination of the low concentration sulfite and sulfate in seawater.