Spectrophotometric determination of periodate with amodiaquine dihydrochloride and its application to the indirect determination of some organic compounds via the malaprade reaction

Periodate has been determined at the p.p.m. level by it's reaction between pH 7 and 8.5 with amodiaquine dihydrochloride [7-chloro-4-(3′-diethylaminomethyl-4′-hydroxylanilino)quinoline dihydrochloride] which yields a chromogen believed to be a 1,4-benzoquinoneimine. The chromogen is extracted into chloroform for spectrophotometric measurement. The maximum molar absorptivity at 442 nm is 2.03 × 103 l mol–1 cm–1 and Beer's law is valid over the concentration range 10–60 p.p.m. with an over-all relative standard deviation of 0.7%. No interference is caused by a 100-fold (m/m) excess of iodate and this has enabled the method to be used for the indirect determination of ethylene glycol, glycerol and tartaric acid via the Malaprade reaction.