Baadenhuijsen H, Seuren-Jacobs H E, Jansen A P
Clin Chem. 1977 Jul;23(7):1275-80.
The merits of the vanadomolybdate method in the determination of inorganic phosphate are highly underestimated with regard to the simplicity of the method and the stability of both the reagents and the color that is formed. The absorption curve of the phosphovanadomolybdate complex, with its maximum at 335 nm, extends into the visible range of the spectrum. This permits measurements with inexpensive tungsten-lamp colorimeters. On-stream dialysis is best done in a nitric acid medium, 0.15 mol/liter. Paralleled by the change in the H2PO4-/H3PO4 ratio, appreciable protein binding and poor dialysis efficiency are seen at lower acid concentrations (pH greater than 1.0). Optimum reaction-mixture concentrations of vanadium and molybdenum appeared to be respectively 0.2 and 5 mmol/liter up to 3 mmol of phosphate per liter, in a final acid medium of 0.2 mol/liter, concentrations considerably lower than those used in some studies published earlier. Color development with the stable combined reagent is complete after only 20 s at room temperature and the color is stable for at least 2 h. Figures on precision and accuracy demonstrate the reliability of the method.
就方法的简便性以及试剂和所形成颜色的稳定性而言，钒钼酸盐法在测定无机磷酸盐方面的优点被严重低估了。磷钒钼酸盐络合物的吸收曲线在335nm处有最大值，延伸至光谱的可见光范围。这使得可以使用廉价的钨灯比色计进行测量。在线透析最好在0.15mol/L的硝酸介质中进行。在较低酸浓度（pH大于1.0）时，伴随着H2PO4-/H3PO4比例的变化，会出现明显的蛋白质结合和较差的透析效率。在最终酸介质为0.2mol/L的情况下，对于每升高达3mmol的磷酸盐，钒和钼的最佳反应混合物浓度分别为0.2和5mmol/L，这一浓度远低于早期发表的一些研究中所使用的浓度。使用稳定的混合试剂在室温下仅20秒即可完成显色，且颜色至少稳定2小时。精密度和准确度数据证明了该方法的可靠性。
