三乙醇胺-磷钼蓝光度法快速测定钢中磷

针对用NaF-SnCl₂作还原剂的磷钼蓝光度法测定钢铁中磷的显色不稳定,进一步研究了该法的显色条件,并在显色体系中加入三乙醇胺作为显色反应稳定剂。结果表明,三乙醇胺对该体系具有良好的稳定作用,显色液在室温下放置5 min后,能使磷钼蓝的吸光度值稳定50 min以上。当磷的含量在0.00～1.00 μg/mL 范围内时,吸光度与浓度呈良好的线性关系。实验方法用于钢中磷含量的测定时,结果稳定,相对误差小于5%,RSD在1.5%～3.2%之间,加标回收率在98.7%～103.2%之间,表观摩尔吸光系数ε_{max,700 nm}=3.18×10⁴ L· mol^-1· cm^-1。方法容易掌握,适用于钢中磷含量的快速和准确测定。

Rapid determination of phosphorus in steel by triethanolamine-phosphorus molybdenum blue spectrophotometry

The coloring was not stable for the determination of phosphorus in steel by phosphorus molybdenum blue spectrophotometry when NaF-SnCl₂ was used as reducing reagent. The coloring conditions of this method were further studied. The triethanolamine was added into coloring system and used as the stabilizer of coloring reaction. The results showed that the triethanolamine exhibited good stabilizing action in this system. As the solution was placed at room temperature for 5 min, the absorbance of phosphorus molybdenum blue system could be stable for more than 50 min. The absorbance showed good linearity to the concentration of phosphorus in range of 0.00-1.00 μg/mL. The proposed method was applied to the determination of phosphorus content in steel standard samples, and the found results were stable. The relative error was less than 5 %, and the relative standard deviation (RSD) was 1.5%-3.2%. The recoveries were between 98.7% and 103.2%. The apparent molar absorptivity was ε_{max, 700 nm}=3.18×10⁴ L· mol^-1· cm^-1. This method was easily mastered, and it was suitable for the rapid and accurate determination of phosphorus in steel.