偶氮硝膦-Ⅰ分光光度法快速测定硅酸盐岩石矿物中的氧化镁

Rapid Spectrophotometric Determination of Magnesium Oxide in Silicate Rocks and Minerals by Nitrophos phonazo-I

变色酸的单偶氮衍生物,如偶氮氯膦-Ⅰ和兴多偶氮氯膦-Ⅰ,均是测定镁的较好试剂。近年来已用于多种材料中镁的测定。偶氮硝膦-Ⅰ以强吸电子基团硝基代替了偶氮氯膦-Ⅰ分子中的氯,所以光度法测定镁时显示了一定的优点,同时镁的线性范围扩大了.

Magnesium forms a purple 1:1 complex with nitrophosphonazo-Ⅰrapidly in the presence of borax-sodium hydroxide buffer (pH 9.42), which exhibits maximum absorbance at 580 nm and its molar absorptivity is 1.4 × 10^(4)l·mol^(-1)·cm^(-1). Beer’s law is obeyed over the range 0-40μg magnisum oxide in 25 ml of solution. Interfering ions can be masked by the addition of triethanolamine and o-phenanthroline. This method has been applied to the spectrophotometric determination of magnesium oxide in silicate rocks and minerals.