Fourier transform infrared spectrometric determination of thiourea in the presence of sulphur dioxide in aqueous solution

An analytical procedure has been developed for quantitative determination of thiourea in aqueous solution acidified with sulphuric acid in the presence of sulphur dioxide. The method is based on the partial least squares treatment of data obtained by attenuated total reflectance Fourier transform infrared spectrometric method in the wave number range 1350¯1450 cm-1 and not required any sample pre-treatment. Absorbance spectra were employed for measurement using a set of 14 aqueous standard solutions of thiourea. The method is valid in the presence of high concentration of sulphur dioxide and inorganic salts. This is particularly important with respect to the use of such solutions for the leaching of gold from ores and concentrates. The method is simple, rapid, accurate (to within ±0.07%) and has been applied to the study of solutions used in leaching experiments.