磷化液中钼的分光光度法测定

Spectrophotometric Determination of Molybdenum in Phosphating Solution

采用硫氰酸盐为显色剂的分光光度法,直接测定在磷化液中以钼酸盐作为磷化加速剂里的钼,采用弱还原剂硫脲,用铜盐催化加快显色速度,用Fe2+为显色液的稳定剂,生成的橙红色配合物。经试验测定钼在50～300μg范围内,符合比耳定律。λmax=460 nm;摩尔吸光系数ε460=9.65×103;回归方程为:A=2.01×10-3.ρ+0.084;相关系数=0.999。方法具有操作简单、准确度高的优点。

Spectrophotometry with thiocyanate as developer was employed to directly determining molybdenum in molybdate used as an accelerator in phosphating solution. This method uses a weak reducing agent thiourea, a copper salt as a catalyst to speed up the developing reaction and Fe^2＋ as a stablizer of the developed solution forming an orange red complex. It is determined through experiment testing that when molybdenum in the solution is in the range of 1 000-6 000 μg/L the solution conforms to the Bill law. The maximum absorption wavelength λmax=460 nm. The mol absorptivity ε460=9.65×10^3. The regression equation is A=2.01×10^-3·ρ＋0.084. The correlation coefficient r is 0. 999. This method has advantages of simple in operation and high accuracy.