Morpholine as an absorbing reagent for the determination of sulphur dioxide

Abstract

Several methods have been developed for the determination of sulphur dioxide in the environment, although some involve the use of hazardous mercury salts. A method is described of trapping sulphur dioxide by forming an adduct with morpholine. Sulphur dioxide is determined in the adduct using p-rosaniline hydrochloride, which forms a coloured complex with maximum absorption at 560 nm. The method is sensitive and a 0.025 µg ml^–1 concentration of sulphur dioxide can be determined in solution. Interferences from Cu(II), Pb(II), Mn(II), Fe(III), Cr(III), V(V), nitrite and hydrogen sulphide have been studied. In addition concentrations of morpholine thrown into the atmosphere by this method have been investigated to assess any possible hazards due to the use of morpholine as a trapping agent during the sampling process.