Determination of phosphate in fluorosilicic acid by phosphorous antimony molybdenum blue spectrophotometry
Yang Zhanju, Ren Zhonghu, Liu Zeju, Ma Fuyuan, An Dong, Xie Wei, Wang Chengyan, Luo Yanjuan
Qinghai west mine tongxin chemical co., LTD., Xining 811600, China
摘要：建立磷锑钼蓝分光光度法测定氟硅酸中磷酸根含量的方法。在氟硅酸样品中加入高氯酸高温挥发除去HF、SiF4 等挥发性的物质，在弱酸性的介质中磷与锑、钼酸铵形成杂多酸，用抗坏血酸还原为磷锑钼蓝络合物，用分光光度计在705nm 波长下测定氟硅酸中磷酸根含量。研究了测定波长、样品酸度、还原剂浓度、还原时间、酒石酸锑钾用量、干扰元素对测定结果的影响，并确定了最佳分析条件：测定波长为705 nm，盐酸溶液（1+1）加入量为1.3 mL，酒石酸锑钾溶液（3 g/L）加入量为0.5 mL，抗坏血酸溶液（20 g/L）加入量为1.5 mL，还原时间为10 min。在此实验条件下，磷酸根的质量浓度在0～15 μg/mL 与吸光度具有良好的线性关系，线性相关系数为0.999 8，检出限为0.051 μg/mL。测定结果的相对标准偏差为2.27%～2.38%（n=11），加标回收率为97.34%～102.72%。该方法操作简单，测试结果准确度和精密度较高，可满足氟硅酸中磷酸根含量的测定，用于氟硅酸生产的质量控制。
Abstract：A method for the determination of phosphate in fluorosilicic acid was established by phosphorous antimony molybdenum blue spectrophotometry. Volatile substances such as HF and SiF4 in sample were removed by adding perchloric acid and high temperature volatilization, and heteropoly acid was formed by phosphorus, antimony and ammonium molybdate in weakly acidic medium, which was reduced to phosphorous antimony molybdate blue complex by ascorbic acid, and the phosphate content in fluorosilicic acid was determined by spectrophotometry at 705 nm wavelength. The effects of absorption wavelength, sample acidity, reducing agent concentration, reduction time, amount of antimony potassium tartrate and interfering elements on the determination results were studied, and the optimal analysis condition was followed: the determination wavelength was 705 nm, the amount of hydrochloric acid solution (1+1) added was 1.3 mL, the addition amount of antimony potassium tartrate solution (3 g/L) and ascorbic acid solution (20 g/L) was 0.5 and 1.5 mL, and the reduction time was 10 min. The mass concentration of phosphate between 0 and 15 μg/mL had a good linear relationship with absorbance, the linear correlation coefficient was 0.999 8, and the detection limit was 0.051 μg/mL. The relative standard deviation of determination results was 2.27%-2.38%(n=11), and the recovery was 97.34%-102.72%. The method is simple to operate with high accuracy and precision, which can be used for the quality control of the production of fluorosilicic acid by the determination of phosphate in fluorosilicic acid.
Keywords：fluorosilicic acid; phosphoric acid root; ammonium molybdate; spectrophotometry
杨占菊，任忠虎，刘泽巨，等. 磷锑钼蓝分光光度法测定氟硅酸中的磷酸根[J]. 化学分析计量，2021，30(2)：37.
Yang Zhanju，Ren Zhonghu，Liu Zeju，et al. Determination of phosphate in fluorosilicic acid by phosphorous antimony molybdenum blue spectrophotometry[J]. Chemical Analysis and Meterage，2021，30(2)：37.