PLANAR CHROMATOGRAPHY AS A METHOD OF FRACTIONATION OF A COAL-LIQUEFACTION EXTRACT FOR MOSSBAUER-SPECTROSCOPY

In previous work, fractionation into solubility classes and by planar chromatography has aided observation of the distinct characteristics o f some less abundant fractions of coal-derived liquids, notably in cas es where the signal from the less abundant fraction would otherwise ha ve been swamped by that from the rest of the sample, In this study, fr actions of a coal liquefaction extract have been separated by planar c hromatography and characterized by Mossbauer spectroscopy, size- exclu sion chromatography (SEC), and UV-fluorescence spectroscopy (UV-F), in an attempt to distinguish between the forms and chemical environments of iron found in the coal extract. Size-exclusion chromatograms and U V-F spectra clearly showed structural differences between the separate d fractions, The iron complexes present in these fractions gave Mossba uer spectra that were similar to each other, however, and to the spect rum of the whole extract. The work indicates that the Fe2+ and Fe3+ io ns are held in similar environments within molecules of different pola rities and complexities spanning the range of the separated fractions, No evidence has been found for chemical reaction between the iron cen ters and the solvents used for the separation, Although Mossbauer dete rminations are not quantitative, similarities between spectral intensi ties suggest that the three fractions contain approximately similar am ounts of iron.