三溴偶氮胂(TBA)已用于粮食、头发、土壤中微量稀土的测定。本文研究了该试剂双波长分光光度法测定微量铋的条件,在0.3mol/L硫酸介质中,Bi-TBA络合物的最大吸收位于630nm处,试剂的最大吸收位于520nm处。采用双峰双波长法测定,表观摩尔吸光系数为1.3×10~5,比单波长法提高了60％。显色反应瞬时完成,络合物至少稳定8h,铋量在0—25μg/25mL范围内符合比尔定律。在拟定的条件下,对10μg铋,误差不超过5％时,允许下列的元素 Tribromoarsenazo (TBA) has been used for determination of trace rare earths in food, hair and soil. In this paper, the conditions for the determination of trace amounts of bismuth with the reagent dual-wavelength spectrophotometry were studied. The maximum absorption of Bi-TBA complex was at 630nm in 0.3mol / L sulfuric acid medium and the maximum absorption of the reagent was at 520nm. The apparent molar absorptivity was 1.3 × 10 ~ 5, which was 60% higher than that of the single wavelength method. The color reaction was completed instantaneously, the complex was stable for at least 8 h, and Beer’s law was obeyed in the range of 0-25 μg / 25 mL bismuth. Under the proposed conditions, 10μg of bismuth, the error does not exceed 5%, allowing the following elements