Document Abstract
A new selective and sensitive kinetic method has been developed for spectrophotometric determination
of methyl parathion based on its inhibitory effect on the redox reaction between bromate and hydrochloric
acid. The decolorization of neutral red by the reaction product was used to monitor the reaction spectrophotometrically
at 530 nm by measuring the change in absorbance at the fixed time of 5 min after the
initiation of the reaction. The variables affecting the rate of the reaction were investigated. Under the
selected experimental conditions methyl parathion was determined in the range of 0.025–0.3 lgmL1.
Sandell’s sensitivity and molar absorptivity for the system were found to be 0.0004 lg cm2 and
6.5 105 L mol1 cm1 respectively. The proposed method was applied for the determination of methyl
parathion in different vegetable and water samples with satisfactory results. The results were compared
with those obtained by GC–MS, very similar values were found by the two methods.