Sensitive spectrophotometric determination of trace quantities of phenylhydrazine

A method for the rapid and accurate determination of trace quantities of phenylhydrazine based on its inhibition effect in the reaction between bromate and hydrochloric acid is developed. The decolorization of methyl orange by the reaction products was used to monitor the reaction spectrophotometrically at 525 nm. The method allows the determination of phenylhydrazine in the range 4.60 x 10(-7)-7.40 x 10(-5) M. The relative standard deviation for 10 determinations of 1.10 X 10(-5) M phenylhydrazine is 0.97% and the detection limit of the method is 1.85 x 10(-7) M. The method is applied to the determination of phenylhydrazine in water. (C) 2001 Elsevier Science B.V. All rights reserved.