Stoichiometry of pyrogallol/ammonium-nitrogen complex using spectrophotometry

Abstract

Pyrogallol (1,2,3-Trihydroxybenzene) forms instantaneous pale-yellow complex with aqueous ammoniumnitrogen (NH4+-N). This complex, which we now refer to as P/NH4 +-N complex, can be the basis for the spectrophotometric determination of NH4 +-N in aqueous solution. Aqueous NH4 +-N is a very important pollution index. Therefore it is imperative that the stoichiometry of this complex be thoroughly understood. In this work, Job’s method of continuous variations and the molar-ratio method were used in a corroborative manner to study and establish the P/NH4 +-N complex as P(NH4)2, where P stands for pyrogllol.