A new induction period based reaction rate method for determination trace amounts of phenylhydrazine in water samples.

A simple, selective, and sensitive kinetic spectrophotometric method is described for the determination of trace amounts of phenylhydrazine, which is based on its inhibition effect on the reaction between meta cresol purple (MCP) and periodate in the presence of bromide ions. The reaction was monitored spectrophotometrically by measuring the change in absorbance of MCP at 525 nm. The calibration graph was linear in the range of 1.0-10.0 microM. The detection limit (3 sigma) was 0.020 microM. The relative standard deviations for 10 replicate measurements of 3.0, 5.0 and 7.0 microM of phenylhydrazine were 2.0%, 1.4%, and 0.90%, respectively. The potential interfering substances were studied in the presence of phenylhydrazine. The proposed method was applied to the analysis of water samples.