分光光度法直接测定矿石中铬

铬在碱性介质中呈黄色，最大吸收波长373 nm处的吸光度与铬的浓度符合比尔定律，据此建立了测定铬的方法。试验了铬的显色条件，确定了显色介质种类、稳定时间。考察了20余种离子的干扰量，表明只有Mn²⁺和Bi³⁺对铬的测定有严重干扰，并提出了有效的消除方法，实现了铬的测定。铬的质量浓度在0.14～14 mg/L范围内符合比尔定律，表观摩尔吸光系数为4.77×10³ L·mol^-1·cm^-1。方法已成功地应用于一般矿石样品中0.5%以上铬的测定。

Direct determination of chromium in ores by spectrophotometry

Chromium is yellow in alkaline medium. The absorbance at the maximum absorption wavelength of 373 nm and the concentration of chromium conforms to Beer's law, the method to determine chromium was established. The coloring condition of chromium was tested to determine the type and stabilization time of color medium. The interference of about 20 ions was studied. The result indicated only Mn²⁺ and Bi³⁺ had serious interference on the determination of chromium. Effective elimination method was also proposed to achieve the determination of chromium. Beer’s law was conformed when the concentration of chromium was 0.14-14 mg/L. The apparent molar absorptivity is 4.77 × 10³ L·mol^-1·cm^-1.The method was successfully applied to the determination of more than 0.5% of chromium in general ore sample.