Leucoquinizarin as an analytical spectrophotometric and fluorimetric reagent: application to the determination of magnesium in pharmaceutical preparations

Abstract

The physico-chemical characteristics and analytical applications of leucoquinizarin are described. The reaction between magnesium and the reagent was studied spectrophotometrically, and a method for the determination of the ion is proposed on the basis of the red complex formed. The spectrophotometric procedure is sensitive (ε₅₆₂= 8.100 l mol^–1 cm^–1) and the colour is developed at pH 9.5 in a solution containing 58%V/V of ethanol. The method has been applied to the determination of magnesium in several pharmaceutical preparations.