BULK COMPOSITIONAL VARIATIONS OF COAL ASPHALTENES STUDIED BY LATENT VARIABLE ANALYSIS OF INFRARED MICROSPECTROSCOPIC DATA

Infrared microspectroscopy in combination with principal component ana lysis (PCA) has been used for the first time to analyze heterogeneous samples. Small areas of asphaltene layers of two asphaltene samples de posited on aluminium mirrors were microspectroscopically analyzed. The same sample size was measured using a masking slit and the measuremen ts were done in a random fashion. PCA was used to reveal the heterogen eity in the bulk of the asphaltenes. Loading plots from PCA were used to extract information on the variation of functional group concentrat ion within the bulk of the asphaltenes. This information was used to g enerate hypotheses about the asphaltene composition of the coal sample s.