Studies on sulphatases. 25. The determination of BaS16O318O by infrared spectroscopy

Abstract

The infrared-absorption spectra of normal barium sulphate and barium sulphate containing 87% of BaS16O318O have been examined. A method of estimating BaS16O318O in barium sulphate has been developed, based on the measurement of relative extinctions at 981 and 961 cm.-l. The method has been used to analyze the barium sulphate prepared from the inorganic sulphate liberated by Aspergillus nidulans arylsulphatase acting on potassium p-nitrophenyl sulphate in the presence of water containing 8.7 atoms % excess of 18O. The BaS16O318O content of the barium sulphate was found to be 7.8%, showing that the type I arylsulphatase of A. nidulans splits the O-S bond of arylsulphates.