A Simple and Low - Cost Spectrophotometric Method for the Determination Of Hydrazine With Methyl Red-iodate System

Abstract

A simple, sensitive and inexpensive spectrophotometric method was developed for the determination of trace amount of hydrazine at microgram level. Hydrazine has been determined by its oxidation to nitrogen by using known excess of potassium iodate. In acidic medium potassium iodate bleaches the methyl red dye. A known excess of potassium iodate was reduced when treated with hydrazine and the unreacted potassium iodate is determined by using methyl red. The method was based on inhibitory effect of hydrazine on the reaction of methyl red dye and potassium iodate in presence of acidic medium. The absorbance of the methyl red after the reaction was monitored spectrophotometrically at 520 nm. The molar absorptivity is calculated to be 3.238×105 L mol-1cm-1. Beer’s law was obeyed over the concentration range of 1-10 µg of hydrazine in an overall aqueous volume of 25 ml with a correlation coeffcient of - 0.999. Sandell’s sensitivity was found to be 0.0004µg cm-2. The optimum reaction conditions like time, temperature, pH, reagent concentration, effect of foreign species etc. have been evaluated for the complete reaction. The developed method can be successfully applied for the determination of trace amount of hydrazine in environmental samples.