鉴于硫离子对硫酸根含量测定的显著性影响，提出了题示方法。当硫离子质量浓度不大于0.10 mg·L^-1时，样品无需预处理直接进样分析；当硫离子质量浓度大于0.10 mg·L^-1时，取50 mL水样，加入2 mL硝酸，于75℃加热40 min，使硫离子完全转化为硫化氢。用水将消解液稀释至50 mL，按照优化的仪器工作条件测定（硫分析谱线选择180.731 nm）。结果显示：硫酸根的质量浓度在1.00~100.00 mg·L^-1内与其对应的谱线强度呈线性关系，检出限（3s）为0.07 mg·L^-1；对实际样品进行加标回收试验，硫酸根的检出量为15.92~90.80 mg·L^-1，回收率为96.8%~103%，测定值的相对标准偏差（n=6）为0.85%~2.8%。

In view of the significant effect of sulfur ion on the determination of sulfate, the title method was proposed. When the mass concentration of sulfur ion was not greater than 0.10 mg·L^-1, the sample was directly introduced for analysis without pretreatment. When the mass concentration of sulfur ion was greater than 0.10 mg·L^-1, 50 mL of water sample was taken and mixed with 2 mL of nitric acid. The mixture was heated at 75℃ for 40 min, so that the sulfur ion was completely converted into hydrogen sulfide. The digestion solution was diluted to 50 mL with water, and determined according to the optimized working conditions of the instrument with sulfur analytical spectral line of 180.731 nm. It was shown that the mass concentrations of the sulfate were linearly related to their corresponding spectral line intensities in the range of 1.00-100.00 mg·L^-1, with detection limit (3s) of 0.07 mg·L^-1. Test for recovery was made by standard addition method on the actual samples, and detected amounts of sulfate were found in the range of 15.92-90.80 mg·L^-1, with values of recovery in the range of 96.8%-103% and RSDs (n=6) of the determined values in the range of 0.85%-2.8%.