对溴偶氮胂光度法测定土壤浸出液和天然水中的微量钙

SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF TRACE CALCIUM IN WATER AND EXTRACT OF SOIL WITH p-Br-ARSENAZO

摘要:

土壤分步浸出液中钙的浓度有时很低,EDTA滴定法难以满足微量分析的要求。近来已有人将对溴偶氮胂用于稀土测定^[1],但对钙的显色反应尚未见报道。我们研究了该试剂在强碱性介质中与钙的反应,认为可用于土壤分步浸出液和天然水中微量钙的测定。

Abstract:

The reagent p-Br-arsenazo, can react with calcium canon (Ca²⁺) in strong basic medium and form:stable green complex with a maximum light absorption at 635nm, The molar extinction coefficient is 9.0×10³, The curve of standard concentration of Ca²⁺ is a straight line in the range of 5-40μg Ca²⁺/25 ml, The interference of Fe³⁺ and Cu²⁺ can be eliminated by adding F^-(or PO₄^3-)and ascorbic acid respectively, while Ag⁺, Co²⁺, Sn⁴⁺, Bi³⁺, Cr³⁺ can be screened by adding trietha-nolamine, The relative errors for determination of Ca²⁺ in well water and extracting of soil samples range from -5.33% to 7.96%.