偶氮氯膦Ⅰ(简称CPA Ⅰ)作为光度显色剂最初应用于测定铀和镤,后又用于测定镉、铜、锆、钍、镧和钇,近年则被应用于测定镁。但应用于测定钙,尚未见国内外报道。本文研究了Ca-CPA Ⅰ络合物的形成条件、组成和稳定常数,应用于土壤水溶性钙镁的连续测定,获得了较满意的结果。 Chlorophosphonazo Ⅰ (referred to as CPA Ⅰ) as a photochromic reagent was initially applied to the determination of uranium and acenaphthene, and later used in the determination of cadmium, copper, zirconium, thorium, lanthanum and yttrium. In recent years, it has been applied to the determination of magnesium. However, applied to the determination of calcium, has not been reported at home and abroad. In this paper, the formation conditions, composition and stability constants of Ca-CPA Ⅰ complex were studied and applied to the continuous determination of water-soluble calcium and magnesium in soil. The satisfactory results were obtained.