Spectrophotometric Determination of Sulphamerazine Via Diazotization and Coupling with m-Hydroxyaniline

Abstract

A simple and accurate spectrophotometric method has been developed based on diazotization and coupling reactions. The method relied on the diazotization of sulphamerazine (SMEZ) via reaction with HNO2 obtained from the reaction of hydrochloric acid with sodium nitrite. The un-reacted nitrous acid destroyed via a reaction with sulphamic acid. The formed diazotized sulphamerazine (D-SMEZ) was coupled with m-hydroxylaniline to produce yellow azo dye, which gives the highest absorption at 450 nm. The formed azo dye is freely soluble in water and has good stability. The linearity is observed by drawing absorbance of various amounts of sulphamerazine from 0. 5 to 25 μg.mL-1, which exhibits molar absorptivity of 1.4592x105 l.mol.-1cm-1 and Sandell's sensitivity factor 0.001811 μg.cm-2. The low detection limit, low quantitation limit, relative error, and percent relative standard deviation have been estimated, and their values are 0.0022 and 0.0076 μg.mL-1 as well as 0.02 to 0.2%, respectively. The present method has successfully been applied to determine sulphamerazine in trisulphoprim injection (veterinary drug).