铀试剂Ⅲ光度法测定钍一般能满足岩石矿物分析要求,但对ppm级钍的化探样品的分析,由于试剂质量问题难以达到要求。偶氮氯膦Ⅲ虽然灵敏度较高,但需用有机溶剂萃取,且稀土和铀的干扰严重。偶氮氯膦mA[2-(4—氯—2—膦酸—苯偶氮)—7—(3—乙酰苯偶氮)—1,8—二羟基萘—3,6—二磺酸)]作为 Uranium reagent spectrophotometry spectrophotometric determination of thorium generally meet the requirements of rock and mineral analysis, but the analysis of the geochemical exploration samples of ppm grade thorium, because of the quality of the reagent is difficult to meet the requirements. Chlorophosphonazo III, although highly sensitive, requires extraction with organic solvents and has serious interference with rare earths and uranium. Chlorophosphonazo mA [2- (4-chloro-2-phosphono-phenylazo) -7- (3-acetophenylazo) -1,8-dihydroxynaphthalene-3,6-disulfonic acid) ] As