PRACTICAL CONSIDERATIONS FOR USING REFLECTANCE SPECTROSCOPY AS A SCREENING TOOL FOR GEOPORPHYRINS

Reflectance spectroscopy of powdered shale samples can be used as an effective screening technique for geoporphyrins. The porphyrins are identified by their characteristic absorption bands which are superimposed on a sloping continuum that results primarily from intervalence electronic transitions in iron. The porphyrin absorptions are a composite of the spectral contributions of all porphyrin species in the bitumen and kerogen fractions. This composite spectrum can be interpreted in terms of porphyrin geochemical parameters provided uncertainties introduced by the sample preparation, spectrum measurement, and data reduction steps are minimized. © 1990, American Chemical Society. All rights reserved.