2─（5─溴─2─毗啶偶氮）─5─二乙氨基酚树脂相分光光度法测定铁矿中痕量钛

2-(5-Bromo-2-Pyridylazo)-5-Diethyl Aminophenol Resin-Phase Spectrophotometric Determination of Trace Titanium in Iron Ores

离子交换树脂可吸附金属有色配合物，通过直接测定已经吸附了金属有色配合物的树脂相的吸光度，不需预浓缩或分离，可检测样品溶液中痕量金属离子的含量。研究了Ｔｉ（Ⅳ）─Ｈ＿２Ｏ＿２─５─Ｂｒ─ＰＡＤＡＰ（２─（５─溴─２─毗啶偶氮）─５─二乙氨基酚）形成的三元异配合物定量吸附于树脂上的实验条件，在ｐＨ３．０～５．０的酸性介质中，加入草酸钠掩蔽铁（Ⅲ）后，在过氧化氢存在下，使Ｔｉ（Ⅳ）与５─Ｂｒ─ＰＡＤＡＰ显色并与树脂混合搅拌１５ｍｉｎ，吸附达平衡，树脂相配合物的最大吸收波长位于６２０ｎｍ；表现摩尔吸光系数为３．６５×１０￣５Ｌ·ｍｏｌ￣（－１）·ｃｍ￣（－１）；钛含量在０～５μｇ／２５ｍｌ范围内符合比耳定律；测定铁矿中的痕量钛，相对标准偏差为１．４％；回收率为９９％～１０１％。

he resin-phase spectrophotometry has various advantages for trace analysis. Concentrationand selective absorption of the chemical components to be identified may occur simultaneously.The sample components are converted into complex of higher ligand number within ion exchangeresin phase, which leads to a remarkable enhancement of the sensitivity. The resin-phase spectrophotometric analytical method, based on the direct measurement of the resin-phase absorbance af-ter the absorption of sample components, has been applied to the determination of titanium. H_2O_2-Ti-5-Br-PADAP Ternary complex at pH3.0～5.0 was adsorbed on the D152H modelweak acidic cation exchange resin, The sodium oxalate are added for masking iron (Ⅲ). The directmeasurement of absorbance by an ion-exchange resin phase which has absorbed a Ternary Com-plex of Titanium is completed. The apparent molar absorptivity is 3.65×10￣5L·mol￣(-1)·cm￣(-1) at620 nm; and Beer's law is obeyed in range of 0～5μg/25 ml for Titanium(Ⅳ). The relative stan-dard deviation is 1.4% and the recovery rate is 99%～101%. This method has a higher sensitivityand a better selectivity than the usual spectrophotometry.