r=0.9999(n=5) and the precision was well with theRSD of3.08%.The lowest detection limitation was O.06ng/m1.(1 21Inthe assay of the content,the standard absorption coeffi cient was 862. Itsstable in 24hours.RSD was 0.50%.ReproducibilitV and the middle precision were both excellent.The average — recovery rate was 99.22%and RSD was 0.37%.The content ofthree batches ofsamples were 99.43%.99.78%and 99.55 %.repectively. Conclusion:The physical and chemical constants. properties ofCarbazochrome Sodium Sulfonate,purity test and assay were studied inthe paper.It iSthe firsttime to establish a method to check the related substances.This would setup abasis fordrawing thequality control standard. Key words: Carbazochrome Sodium Sulfonate, identification,test,assay,RP—HPLC,UV’quality control standard 9