在硫酸介质中,BrO3-氧化I-形成I3-络阴离子,I3-络阴离子可进一步与结晶紫阳离子形成离子缔合物,在聚乙烯醇存在下,缔合物呈清亮的浅棕红色溶液,以试剂空白为参比,最大吸收波长为542 nm,吸光度与BrO3-浓度呈线性关系,线性范围为0.5~3.5μg/10 mL,表观摩尔吸光系数为1.02×105 L/(mol•cm),检出限为0.016μg/mL,样品回收率为95.2%~101.4%,RSD为2.69%。将该方法用于面粉中微量溴酸钾测定,结果令人满意。%A highly sensitive spectrophotometry method was used to determine trace amounts of KBrO3 based on the oxidation of I- to I3- by BrO3- and the further reaction of I3- with crystal violet to form the ion-association complex in sulfuric acid medium. In the PVA, the complex was transparent brownish-red. The maximum absorption wavelength was 542 nm against reagent blank. It was found that the absolute value of the maximum absorption wavelength was proportional to the BrO3- con-centration. Beer’s law was obeyed in the rang of 0.5~3.5μg/10 mL. The apparent molar absorption coefficient was 1.02×105 L•mol-1•cm-1, with detection limit of 0.016μg/mL. The spiked recoveries were 95.2%~101.4%,with the RSD of 2.69%. The method was used to determine trace bromate in wheat flour with satisfactory results.
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