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目前,关于稀土总量的测定方法为数不少,如偶氮胂Ⅲ[1]和偶氮氯膦Ⅲ[1]等作为显色剂的吸光光度法应用较为普遍,但是,对复杂试样中低含量的稀土总量测定,往往需要经过较冗长的分离手续后,才进行光度法测定。因此,进一步探索能在较强酸性介质中,具有高灵敏度及高选择性的稀土显色剂及其显色反应体系,实属必要。几年来我们合成了一系列含膦酸基的不对称变色酸双偶氮衍生物,对碘偶氮氯膦(P—Iodochlorophosphonazo简写P—ICP)就是其中之一[2]。试剂化学名称为2-(4-氯-2-膦酸基苯偶氮)-7-(4-碘苯偶氮)-1,8-二羟基萘-3,6-二磺酸。该试剂提纯、鉴定采用硅胶板上的薄层色谱法,纯度90%左右,产品为暗紫色粉末,溶于水,微溶于乙醇、丙酮,但不溶
At present, there are quite a few methods for the determination of the total amount of rare earths. The spectrophotometric methods such as arsenazo III [1] and chlorophosphonazo III [1] are more common. However, in complex samples Determination of the low content of rare earth, often need to go through a more lengthy separation procedures before the photometric determination. Therefore, to further explore the strong acid medium, with high sensitivity and high selectivity rare earth color reagent and its color reaction system, it is necessary. For several years we have synthesized a series of asymmetric chromotropic acid disazo derivatives containing phosphonic acid groups, one of which is P-Iodochlorophosphonazo (P-ICP). The chemical name of the reagent is 2- (4-chloro-2-phosphonophenylazo) -7- (4-iodophenylazo) -1,8-dihydroxynaphthalene-3,6-disulfonic acid. The reagent was purified and identified by thin-layer chromatography on silica gel plate with a purity of about 90%. The product was dark purple powder, soluble in water, slightly soluble in ethanol and acetone but insoluble