5-Br-PADAP-IO_3-SCN^-三元离子缔合物测定微量IO_3^-的研究

Spectrophotometric Determination of IO_3^- with 2- (5 - Bromo- 2 - pyridylazo ) - 5 - Diethylaminophenol and SCN-

本文研究了２－（５－溴－２－吡啶偶氮）－５－二乙氨基酚（５──Ｂｒ─ＰＡＤＡＰ）在酸性介质中质子化，与ＩＯ_３~－和ＳＣＮ－形成三元离子缔合物的最佳条件，其最大吸收波长在５５０ｎｍ处，表观摩尔吸光系数为５．８×１０~ ４Ｌ·ｍｏｌ^（－１）·ｃｍ^（－１），缔合物的组成比为 ５－Ｂｒ──ＰＡＤＡＰ： ＩＯ_３~－： ＳＣＮ~－＝２：１： ４。提供了测定微量ＩＯ_３~－的新方法，用于加碘食盐及海带等样品中含碘量的测定，回收率为９７．３％～９８．０％，相对标准偏差为０．９３％～１．７０％，结果令人满意。

The optimum conditions of ion association of protonated 2 - (5 - bromo - 2 - pyridylazo) - 5- diethylaminopenol (5-Br-PADAP) with IO_3^- and SCN-- formed in H_2SO_4 medium was investigated in this paper. There is a maximum absorbance at 550 nm. The molar absorptivity is 5.8×10~4L. mol^(-l). cm^(-1) and the composition ratio of 5-Br-PADAP: IO_3^-: SCN-is 2:1:4. A new method for the determination of microamount of IO_3^- was developed and applied to determine microamount of iodine in table salt with satisfactory results. The recovery is 97.3%-98.0%. The relative standard deviation is 0.93K-1.70%.