An Alternative Method for Sample Preparation of Coal for Examination by Infrared Spectroscopy

Abstract

The limitations inherent in the traditional method of preparation of coal for examination by infrared spectroscopy, i.e. the alkali halide disc method, are well documented. Friedel et al. clearly showed the need for fine and, therefore, prolonged grinding to produce acceptable spectra and demonstrated how this produces the KBr/H2O interaction bands that mask the —OH stretching bands. Painter et al. avoided these problems by grinding the coal in fluorolube following the method described by Brady. This, however, left a strongly sloping base line that could be partially overcome by standard base line correction procedures available on computerized instruments. The difficulties experienced in measuring the hydroxyl functional groups in coal were also discussed by Painter et al. in a later paper and it was concluded that a combination of Fourier transform infrared (FT-IR) and chemical procedures was required.