电感耦合等离子体原子发射光谱法间接测定地表水和地下水中硫酸根

建立了电感耦合等离子体原子发射光谱法间接测定地表水和地下水中硫酸根的方法。样品经盐酸(1+1)酸化,煮沸除去碳酸根、硫化物等干扰物质后,通过加入适量的钡标准溶液将溶液中的硫酸根沉淀,再用0.45 μm滤膜干抽滤,收集滤液。以Ba 233.527 nm作为分析线,采用电感耦合等离子体原子发射光谱法(ICP-AES)测定滤液中的钡量,通过用加入的钡总量减去滤液中的钡量,计算得到沉淀样品中硫酸根所消耗的钡量,从而再间接计算出样品中硫酸根的量。据此,实现了地下水和地表水中硫酸根的测定。实验表明:地表和地下水样中的钙、镁、铝、铁、钾、钠对测定的影响可忽略;50.00 mL水样中加入3.0 mL盐酸(1+1)酸化时对测定的影响可忽略。在选定的实验条件下,钡的质量浓度在1.00～50.00 μg/mL范围内与其对应的发射强度呈线性关系,校准曲线的线性相关系数r=0.999 9。实验方法用于地表水和地下水样品中硫酸根的测定,测定结果与离子色谱法、铬酸钡分光光度法和比浊法相吻合,相对标准偏差(RSD,n=7)小于2.0%。

Indirect determination of sulfate in surface water and groundwater by inductively coupled plasma atomic emission spectrometry

An indirect determination method of sulfate in surface water and groundwater by inductively coupled plasma atomic emission spectrometry was established. After the sample was acidified by hydrochloric acid(1+1) and the interference materials such as carbonate and sulfide was removed by boiling, proper amount of barium standard solution was added to precipitate the sulfate in the solution. The filtrate was collected by dry suction filtration with 0.45 μm filtration membrane. The content of barium in filtrate was determined by inductively coupled plasma atomic emission spectrometry(ICP-AES) with Ba 233.527 nm as analytical line. The consumed amount of barium by sulfate in precipitate could be calculated by subtracting the content of barium in filtrate from total amount of barium added. Thus, the content of sulfate in sample could be indirectly calculated, realizing the determination of sulfate in surface water and groundwater. The results showed that the influence of calcium, magnesium, aluminum, iron, potassium and sodium in surface water and groundwater on determination could be ignored. Meanwhile, the influence of 3.0 mL of hydrochloric acid(1+1) for the acidification of 50.00 mL of water sample could be also ignored. Under the selected experimental conditions, the mass concentration of barium in range of 1.00-50.00 μg/mL was linear to the corresponding emission intensity. The linear correlation coefficient of calibration curve was r=0.999 9. The proposed method was applied to the determination of sulfate in surface water and groundwater samples. The results were consistent with those obtained by ion chromatography, barium chromate spectrophotometry and turbidimetry. The relative standard deviation (RSD, n=7) was less than 2.0%.