基于聚乙烯醇(PVA)比浊法研究并建立了柠檬酸溶液中硫酸根离子的分析方法,探讨了检测波长、柠檬酸浓度和聚乙烯醇浓度对硫酸钡分散体系的影响。研究表明,聚乙烯醇可提高柠檬酸液中硫酸钡颗粒的形成速率以及分散体系的稳定时间。检测波长为440 nm,聚乙烯醇浓度为1.0 g/L时,低于3.0%的柠檬酸溶液中,硫酸根离子的线性范围为2-24 mg/L,线性方程为A=0.010 6C-0.018 3(A和C分别为吸光度和硫酸根离子质量浓度,R2=0.9976)。分析方法的重复性RSD为0.73%,加标回收率为97.5%-102.9%。此分析方法快速、简便,可准确分析柠檬酸液中的硫酸根离子。

Sulfate ion content in citric acid solution by turbidimetric analysis method was studied and established.The effects of wavelength,citric acid and polyvinyl alcohol(PVA) concentration on the stability time and absorbance intensity were analyzed in detail.Results indicated that the crystallization rate of BaSO4 precipitation could be enhanced by addition PVA in the citric acid solution,and the stability of suspension was improved by increasing the concentration of PVA.Also,the optimal absorbance wavelength was 440 nm and the optimal PVA concentration was 1.0g/L,citric acid solution was less than 3%.The linear range of standard curve was 2~24 mg/L,and its equation was expressed as A=0.010 6C-0.018 3(A is the absorbance and C is the mass concentration of sulfate,R2=0.997 6).The reproducibility RSD was 0.73% and the recoveries were 97.5%~102.9%.The analytical method established in this work can be applied to accurate and rapid determination of sulfate ion in the citric acid.