本文介绍了新显色剂3′-膦酸基偶氮胂的合成,并研究了分光光度法测定铬(Ⅲ)的条件。在pH2.0时铬(Ⅲ)与该试剂经水浴煮沸15分钟生成1:1蓝色络合物,其最大吸收峰在630毫微米处,克分子吸光系数为3.5×10~4,铬量在0～1.2μg ml~(-1)范围内遵守比尔定律。用此法测定了钢样中的铬。 In this paper, the synthesis of a new chromogenic reagent 3’-phosphonazoarsine was introduced and the conditions of spectrophotometric determination of chromium (Ⅲ) were studied. At pH2.0 chromium (Ⅲ) and the reagent boiled for 15 minutes in a water bath to generate 1: 1 blue complex, the maximum absorption peak at 630 nm, the molecular absorption coefficient of 3.5 × 10 ~ 4, the amount of chromium Beer’s law is obeyed in the range of 0 ~ 1.2μg ml ~ (-1). This method was used to determine the chromium in steel samples.