偶氮氯膦Ⅲ比色法测定褐藻胶中微量钙

Colorimetric Determination of the Trace Calcium in the Sodium Alginate Using Chlorophosphonazo Ⅲ

作者研究了以偶氮氟膦Ⅲ比色测定褐藻胶中微量钙的方法。在溶液pH为3.0～3.5时,钙与偶氮氯膦Ⅲ形成绿蓝色络合物,络合物最大吸收波长在620nm处,摩尔吸光系数为9.2×103。络合物组成为1:1,钙的回收率为98.0～106.0％,可用EDTA或NH4F、8—羟基喹啉掩蔽铁、铝、锌、镁。本方法可测出褐藻胶中1％以下的钙。

In this paper, the method for determining the trace calcium content in the sodium alginate through chlorophosphonazo Ⅲ colorimetric has been studied. In the solution, pH 3.0 to 3.5, calcium reacts with chlorophosphonazo Ⅲ to form green blue complex. The absorbance maximum of the complex are lied at 620 nm and the molar absorptivity is 9.2×10~3. The molar ratio of calcium to chlorophosphonazo Ⅲ is 1 : 1. The recovery of calcium is 98.0～106.0%. The interference of Aluminium, Iron, Magnesium and Zinc can be masked by ammonium fluoride EDTA and 8—hydroxyquinaline. This method can be used for determination of the calcium is less than 1% in sodium alginate.