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磷广泛存在于动植物组织中,不同品种的水果原汁中均含有一定量的磷酸盐,据文献[1]报道,果汁饮料中磷酸盐含量可作为水果原汁含量测定的重要参数。本文应用经典的钼蓝比色法测定果汁饮料中磷酸盐含量,对样品前处理方法进行了探讨,干法消化样品,准确加入一定量稀硫酸处理灰分,经实测样品,加标回收试验,方法精密度和准确度均获得满意的结果。 1 体系酸度的选择氯化亚锡还原钼蓝显色因酸的浓度而异。酸浓度低时,即使不存在磷酸离子,也可因钼酸盐被还原而显蓝色,空白值升高。另外,酸浓度过高时,只有磷钼酸中的钼被还原,不显蓝色。通过多次试验观察,体系中还原酸度控制在[H~+]0.7～1.0mol.L~(-1)时(即
Phosphorus is widely found in animal and plant tissues. Different types of fruit juice contain a certain amount of phosphate. According to the literature [1], the phosphate content of fruit juice drink can be used as an important parameter to determine the content of fruit juice. In this paper, the classical molybdenum blue colorimetry was used to determine the content of phosphate in fruit juice drinks. The sample pretreatment method was discussed. The sample was dry digested and a certain amount of dilute sulfuric acid was added accurately. The tested samples, spiked recovery test, Precision and accuracy are satisfactory results. 1 system, the choice of acidity stannous chloride reduction molybdenum blue color varies depending on the acid concentration. When the acid concentration is low, the molybdate is reduced to a blue color even in the absence of phosphate ions, and the blank value is increased. In addition, the acid concentration is too high, only molybdenum molybdenum molybdenum is reduced, no significant blue. Through many experiments, the reduction acidity of the system was controlled at [H ~ +] 0.7 ~ 1.0mol.L ~ (-1)