Solvent Extraction and Spectrophotometric Determination of Magnesium by Paratoly l-2-Thenohydroxamic Acid and Quinalizarin

Magnesium is extracted with a chloroform solution of N-p-tolyl-2- thenohydroxamic acid (PTTHA) from aqueous solution of pH 9.5 .Mg-PTTHA complex is colourless and the colour is developed by adding quinalizarin into the extract. lmax and e of the complex are 590nm and 2.8´103 Lmol -1cm-1respectively.Most common  ions do not interfere in the determination of magnesium. The spectral characteristics of magnesium complexes with hydroxamic acids are recorded. Magnesium is also determined by AAS and the results are in agreement with those of spectrophotometric method. The method is applied to the determination of magnesium in standard alloy samples.