电感耦合等离子体原子发射光谱法测定水体中硫化物

Determination of sulfides in water body by inductively coupled plasma atomic emission spectrometry

水体中硫化物的测定多采用亚甲基蓝分光光度法和碘量法,但这两种方法均存在检测程序繁琐和检测影响因素较多等问题。试验发现,硫化物经现场加入乙酸锌固定为硫化锌后抽滤,不溶物转入25mL比色管中,加入1.0mL 0.1mol/L氢氧化钠溶液和5.0mL 30%过氧化氢溶液,用水定容后90℃水浴加热50min,硫化锌可定量转化为硫酸锌。再次抽滤后,调整溶液的介质为5%（V/V）硝酸,使用电感耦合等离子体原子发射光谱法（ICP-AES）可测定其中硫含量,从而建立了电感耦合等离子体原子发射光谱法测定水体中硫化物的方法。硫的质量浓度在1.00～200.00mg/L范围内与其发射强度呈线性,校准曲线的相关系数为r=0.999 8。当取样量为2.0L时,方法检出限为0.002 2mg/L,测定下限为0.007 4mg/L。按照实验方法对5个实际水样中硫化物进行全程加标回收试验,硫的回收率为97%～102%。实验方法用于测定3个实际水样中硫化物,测定值与国标GB/T 16489—1996测定结果相吻合;11次测定结果的相对标准偏差（RSD）为0.09%～5.0%。

The determination of sulfides in water body usually adopted methylene blue spectrophotometry and iodometry.However,these two methods had some problems such as complicated detection procedures and many influencing factors.In the study,the zinc acetate was added to convert the sulfides to zinc sulfide.After suction filtration,the insoluble substances were transferred into 25 mL colorimetric tube.Then,1.0mL of 0.1 mol/L sodium hydroxide solution and 5.0 mL of 30% hydrogen peroxide solution were added.After dilution to the mark with water,the solution was heated in water bath at 90 ℃for 50 min.The zinc sulfide could be quantitatively converted to zinc sulfate.After suction filtration again,the solution medium was adjusted to 5%（V/V）nitric acid.The content of sulfur was determined by inductively coupled plasma atomic emission spectrometry（ICP-AES）.Thus the determination method of sulfides in water body by ICP-AES was established.The mass concentration of sulfur in range of 1.00-200.00mg/L had good linearity to the corresponding emission intensity.The correlation coefficient of calibration curve was r=0.999 8.When the sample volume was 2.0L,the detection limit of method was 0.002 2mg/L,and the low limit of determination was 0.007 4mg/L.The recovery tests were conducted using five actual water samples according to the experimental method.The recoveries were between 97% and 102%.The content of sulfides in three actual water samples was determined by the proposed method,and the found results were consistent with those obtained by national standard method（GB/T 16489-1996）.The relative standard deviations（RSD,n=11）were between 0.09% and 5.0%.