Spectrophotometric determination of hydroxylamine and its derivatives in drug formulations by the indophenol reaction

Hydroxylamine has been determined by its reduction to ammonium sulphate in Zn/H2SO4 column and Berthelot reaction of the formed ammonium sulphate using salicylic acid, sodium hypochlorite and sodium nitroprusside to give indophenol blue which is measured spectrophotometrically at 648 nm. The molar absorptivity is found to be 1.9×104 1 mol-1cm-1. Beer's law is obeyed in the range 2.5-25 μg of hydroxylamine in 10 ml of its solution. For the determination of 1.5 μg/ml of hydroxylamine, the RSD is 2.8% (n=10). The developed method has been applied for the determination of hydroxylamine and its derivatives after hydrolysis in drug formulations. The results obtained by the present method compare well with those obtained by the available reference method and with the standard addition of hydroxylamine.