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在过量Br-离子存在下 ,亚硝酸钠选择性氧化I-离子生成I2 ,并与Br-离子形成 [I2 Br]-配阴离子 ,[I2 Br]-可进一步与结晶紫 (CV)形成离子缔合配合物 [CV][I2 Br],此时溶液发生明显的颜色变化 .其最大吸收位于 5 5 0nm处 ,I-离子在 0~ 1 4μg/mL范围遵守比耳定律 .方法具有较高的灵敏度和选择性 ,相当量的其他卤离子、酸根离子及一定量的金属离子不干扰测定 .方法用于海带、紫菜等海产品中磺离子的测定 ,结果满意 .
In the presence of excess Br- ions, sodium nitrite selectively oxidizes I- ions to form I2 and forms [I2Br] -anions with Br- ions, [I2Br] - to further form ionic groups with crystal violet (CV) The complex [CV] [I2Br], when the solution significant color change, the maximum absorption at 550nm, I-ions in the range of 0 ~ 14μg / mL Beer’s law to comply with the method has a higher Sensitivity and selectivity, a considerable amount of other halide ions, acid ions and a certain amount of metal ions do not interfere with the determination. Methods for the determination of sulfonates in kelp, seaweed and other seafood with satisfactory results.