Vitrinite, organic sulfur content

Two factors make it advantageous to measure the organic sulfur content of vitrinite in order to find the organic sulfur content of a coal. The most obvious is that the number of EPM analyses will be fewer. For each of the coal samples listed in... 

Figure 1, Organic sulfur content of coal vs. organic sulfur content of respective vitrinite components for coals listed in Table III (dmmf wt %). All measurements...

Table VII, Raymond et al. ( ) analyzed up to 400 vitrinite grains for organic sulfur content both with and without the aid of photomosaics. Using a t-statistic approach they calculated the number of analyses (n) for each run necessary to give a desired maximum variability of lOJt, at the 95% confidence level, from the true mean as defined by 100 analyses. As can be seen in Table VII, in no case was it necessary to analyze more than 14 vitrinite areas. The second advantage to analyzing only vitrinite is that Raymond et al. ( .) were able to achieve essentially identical results both with and without the use of photomosaics. Using texture and morphology to identify areas of vitrinite after the sample had been placed in the EPM was as successful as identifying the vitrinite using oil-immersion microscopy prior to analysis. It should be noted that only two of the four...

EPM analysis for organic sulfur content can be performed easily on -20 to -100 mesh coal samples. Samples need only be mounted in epoxy and polished similar to how coal samples are commonly prepared for petrographic examination. 15 areas within non-contiguous vitrinite grains are analyzed with the EPM. Without the need to produce a photomosaic, the organic sulfur content of vitrinite, and therefore of a coal, may be determined in less than 10 minutes. 

The data presented in Table V were obtained by energy-dispersive X-ray analysis using an electron microprobe. The method is based on monitoring the sulfur content of an organic maceral (in this case, vitrinite), which is not associated with any cations, as an index of the organic sulfur... 

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