A sensitive spectrophotometric method for the determination of hydroxylamine by use of p-nitroaniline and N-(1-naphthyl)-ethylenediamine

A sensitive method for the spectrophotometric determination of hydroxylamine is described, based on known diazotization and coupling reactions. Hydroxylamine is oxidized by iodine in acetic acid medium to nitrite which then diazotizes p-nitroaniline to form a diazonium salt which is later coupled with N-(1-naphthyl)ethylenediamine to give a purple dye which has an absorption maximum at 545 nm, with a molar absorptivity of 6.6 x 10(4) l.mole(-1).cm(-1). Beer's law is obeyed over the hydroxylamine concentration range 0-8(microg/25 ml) (0.0-0.32 ppm) in the final solution.