7402{[(C_(13)H_(2n+1))_3N~+CH_3]Cl~-,n=8～11}是一种含较长碳链的季铵盐(相当于美国的Aliquat-336)。作为萃取剂,季铵盐的萃取机理与阴离子交换树脂的吸咐相似,因此也称为液体离子交换剂。季铵盐几乎都能不同程度地举取所有的阴离子、络阴离子,所以,其萃取选择性较差。在用萃取-光度法测定金属离子时,为了提高灵敏度,常使季铵盐和络阴离子生成离子对并以有机溶剂萃取。例如用7402萃取 7402 is a quaternary ammonium salt with a long carbon chain (equivalent to Aliquat-336 of U.S.A.) ). As an extractant, the quaternary ammonium salt extraction mechanism is similar to the adsorption of anion exchange resins and is therefore also referred to as a liquid ion exchanger. Almost all quaternary ammonium salts can lift all the anion, complex anion, so its extraction selectivity is poor. In the extraction - photometric determination of metal ions, in order to improve the sensitivity, often quaternary ammonium salts and complex anion ion pairs and organic solvent extraction. For example with 7402 extraction