Spectrophotometric Determination of Magnesium(ll) with 2-Carboxy-2"-hydroxy-3' , 5' -dimethylazobenzene-4- sulphonic Acid

Laxminarayan, Institute of Technology, Nagpur-440 010

Chemistry Department, Nagpur University, Nagpur-440 010

Manuscript received 18 October 1982, revised 24 August 1983, accepted 25 March 1984

2-Carboxy-2'-hydroxy-3',5'-dimethylazobenzene-4-sulphonic acid (CHDMAS) is recommended as a chelating agent for the spectrophotometric determination of magnesium (II). It forms a red coloured complex with magnesium(ll) which can be quantitatively determined at pH 11.0. The complex has absorption maximum at 510 nm and it obeys Beer's law over 0.5 $\mu$g to 16.0 $\mu$g Mg(ll) per ml. The reagent forms 1 : 1 complex with Mg(ll). The method is sensitive and fast.