丁基罗丹明B 褪色分光光度法测定小麦粉中痕量溴酸钾

建立基于丁基罗丹明B-盐酸体系测定小麦粉中痕量溴酸钾的褪色分光光度法。考察酸度、丁基罗丹明浓度和用量、反应时间和温度对测定结果的影响。结果表明，最优化的实验条件为：最大吸收波长558nm，0.3mol/L盐酸反应介质，1.0mL 1×10-4mol/L丁基罗丹明B，80℃水浴条件下加热5min。在优化实验条件下，溴酸钾在0～0.3μg/mL之间存在线性关系，线性方程为δA=1.607C＋0.0057(r=0.9996)，检出限为0.08μg/g，摩尔吸光系数为1.6×106L/(mol ·cm)，将该法用于小麦粉中痕量溴酸钾的测定，样品加标回收率为92%～109%，相对标准偏差小于5%，结果满意。

Spectrophotometric Determination of Trace Potassium Bromate in Wheat Flour Based on Oxidation-Decoloration of Butyl Rhodamine B

A new spectrophotometric method for determining trace potassium bromate in wheat flour based on oxidation-decoloration of butyl rhodamine B (BRB) was established. The effects of some important factors such as acidity, concentration and volume of BRB, reaction time and reaction temperature were investigated to acquire the optimal conditions. The results indicated that the optimal conditions were maximum absorption peak at 558 nm, 0.3 mol/L hydrochloric acid and 1.0 mL 1.00 × 10-4 mol/L BRB solution, reaction temperature of 80 ℃ and reaction time of 5 min. Beer's law was obeyed in the range of 0 to 0.3μg/mL for potassium bromate. The regression equation was δA = 1.607C + 0.0057 (C: μg/mL) with a correlation coefficient of 0.9996. The detection limit was 0.08μg/g with a molar absorption coefficient of 1.6×106 L/(mol ·cm). The developed method was used for the determination of trace potassium bromate in wheat flour with satisfactory results. The recovery rate of samples was in the range of 92%－109% with relative standard deviation of less than 5%.