磷锑钼蓝分光光度法测定大米和面粉中磷

Determination of phosphorus in rice and flour by phosphorus antimony molybdenum blue spectrophotometry

该文采用酸度为0.10 mol/L的硫酸作为介质,磷(Ⅴ)与钼酸铵发生显色反应生成淡黄色络合物,在抗坏血酸和酒石酸锑钾的还原下变成蓝色络合物。在磷锑钼蓝分光光度法的基础上,研究加入铋(Ⅲ)之后对测定磷的影响,发现铋(Ⅲ)的引入,使测定磷的灵敏度提高54.6%。体系最大吸收波长在708 nm,磷含量在0.040~0.90μg/mL范围内与吸光度呈现良好的线性关系,其线性回归方程为A=1.859C+0.079,线性相关系数r=0.999 5,其表观摩尔吸光系数ε708nm=6.19×104L/mol/cm,方法检出限为0.023μg/mL。该法可成功地测定食物大米和面粉中磷的含量。

In this paper, sulfuric acid with acidity of 0.10 mol/L is adopted as medium, and the chromogenic reaction takes place between phosphorus(Ⅴ) and ammonium molybdate with light yellow complex produced, and then it turns into blue complex under the reduction effect of ascorbic acid and antimony potassium tartrate. Bismuth(Ⅲ) is added on the base of phosphorus antimony molybdenum blue spectrophotometric method and the effect of bismuth(Ⅲ) on the determination of phosphorus is studied. It is found that the introduction of bismuth(Ⅲ) has increased the sensitivity of determination for phosphorus by 54.6% and the maximum absorption wavelength of the complex is 708 nm and the absorbance is linearly related to the concentration of phosphorus(Ⅴ) within the range of 0.040-0.90 μg/mL. The linear regression equation is A=1.859 C+0.079, with a correlation coefficient of r is 0.9995. Its apparent molar absorption coefficient ε708 nm is 6.19×104 L/mol/cm and the detection limit of the method is 0.023 μg/mL. The method has been successfully used to determine phosphorus content in foodstuff rice and flour.