In acid medium with polyvinyl alcohol in existence, cadmium(ⅱ) can form water-soluble ternary ionic association with potassium iodide and Rhodamine B respectively. According to this the paper proposes the high sensitivity spectrophotometry to determine cadmium. 在聚乙烯醇存在下的酸性介质中,镉(Ⅱ)分别与碘化钾、罗丹明B形成水溶性的三元离子缔合物,据此提出了测定镉的高灵敏度的分光光度法。