在盐酸介质中 ,二溴对甲偶氮羧与钡形成 2∶1的络合物 ,其最大吸收波长为 60 5nm ,摩尔吸光系数ε =1 75× 1 0 4 ,形成的络合物稳定性好 ,吸光度在 48h内保持不变。显色体系具有较好的选择性 ,大量常见离子不干扰测定。钡量在 0～ 1 6μg/1 0mL范围内符合比尔定律。方法应用于铁合金中微量钡的测定 ,结果满意。 In hydrochloric acid medium, dibromo-p-methylcarboxylazide and barium form a 2: 1 complex with a maximum absorption wavelength of 60 5 nm and a molar extinction coefficient ε = 1 75 × 10 4. The stability of the complex formed Well, the absorbance remains unchanged within 48h. Color system has good selectivity, a large number of common ions do not interfere with the determination. Beer’s law was obeyed in the range of 0 ~ 16μg / 1 0mL. The method was applied to the determination of trace barium in ferroalloys with satisfactory results.