Spectrophotometric determination of periodate with salicylaldehyde guanylhydrazone using flow injection. Determination of glycerol in vegetable oils

Abstract

Periodate has been determined using flow injection with spectrophotometric detection on the basis of the red colour obtained when salicylaldehyde guanylhydrazone (SAG) and periodate were mixed in a basic medium. The carrier stream was de-mineralised water. The reagent stream was an aqueous SAG solution and another stream contained an ammonia buffer (pH 9.2) solution. The calibration graph was linear between 5 and 50 p.p.m. of periodate when the injection volume was 200 µl. The relative standard deviation (n= 10) was 1.0% and the detection limit, corresponding to a signal to noise ratio of 3, was 0.35 p.p.m. The proposed method was applied to the determination of glycerol in vegetable oils using the Malaprade reaction.