HIGH-RESOLUTION STEPPED-COMBUSTION MASS-SPECTROMETRY - APPLICATION TOTHE DETECTION AND ANALYSIS OF FINE-GRAINED DIAMOND IN METEORITES AND ROCKS

An analytical system and operating protocol are described for high res olution, stepped-combustion mass spectrometry, designed for the extrac tion, purification, quantification and isotopic analysis of light elem ents (e.g. C and N) in fine-grained reduced components (e.g. diamond) which have been chemically extracted from natural samples (e.g. meteor ites). Specifically, a simple model has been developed for the extract ion of diamond from meteorite and its analysis by high resolution step ped heating under an atmosphere of oxygen. Changes in the pressure of oxygen within the range 1.3 to 12kPa (10 to 90 torr) were not found to have any detectable effect on the combustion. Results obtained by thi s procedure were compared with those predicted by a model and excellen t agreement was found, taking into account the limitations of this app roach. Results of a preliminary attempt to find fine-grained diamond i n a lamproite are outlined.