【摘要】 在酸性介质中,I-可以被Ce(Ⅳ)氧化为I2,I2与过量的Br-可以形成[I2Br]-配阴离子,[I2Br]-又可和罗丹明B进一步缔合形成三元缔合体系,I2—溴化钾-罗丹明B三元缔合体系具有高灵敏显色特性,适量的表面活性剂十六烷基三甲铵溴化胺(CTMAB)又具有增溶、增敏的作用,缔合物λmax=585nm,基于此建立了流动注射-分光光度法测定微量碘离子快速、简便的新方法。试样经铈(Ⅳ)盐在线氧化后与显色剂混合,水为推动液,在对体系和流路等诸参数进行优化之后,碘离子含量在50～1000μg/L范围内呈线性关系,最低检出限为20μg/L,相对标准偏差为0.85%(n=10)。该方法简便、快捷,选择性较好,常见离子基本无干扰,用于测定海带、紫菜、加碘食盐和海盐中的碘离子,结果令人满意,具有很好的实用性。更多还原

【Abstract】 A new, simple and rapid spectophotometric FI technique for accurate determination of I- has been developed. The method was based on the decrease of absorbance intensity of rhodamine B due to the complexation with [I2Br]-, which I- could be selectively oxidated to form I2 by Ce(Ⅳ) in acidic medium where I2 reacted with Br- to form [I2Br]-. Which I- could be selectively oxidated to form I2 by Ce(IV) in acdic medium where I2 reacted with Br- to form [I2Br]-. At this moment, some changes of the solution’s color took place. It was found useful for sensitivity test in CTMAB media. The absorption peak of the complexation increased linearly by addition of I-, occured at 585nm. Optimization of chemical and FI variables has been made. Under the optimized conditions, the calibration curve obtained was linear over the range 50～1000μg/L, while the detection limit was lower than 20 μg/L, and the precision level ( RSD=0.85%, n=10 ) was found quite satisfactory. This method showed good sensitivity and selectivity. Proper amount of inorganic acid radical ions, metal ions and other halide ions would not interfere the determination. Application of the method to the analysis of I- in kelp, laver, common salt or sea salt would result a good agreement between the expected and found values.更多还原