We don't have CHN analyzer in our laboratory and we want to measure the ultimate analysis of our biomass samples. So, is there any alternative method, technique or procedure or machine through which we can do the CHN analysis of our samples.
Dear Dr A. S. Nizami,
There may be an alternative method to determine the CHN content of your biomass samples. The standard is called ASTM D5373 - 16 but was designed for determining carbon, hydrogen and nitrogen of coal and coke.
However, since most journals and experts accept the results of proximate analysis from ASTM 3172, 3173 and 3175, I would imagine the use of D5373 for ultimate will suffice.
Lastly, EDX and XPS may also be used to determine Carbon, Nitrogen, Sulphur and Oxygen, however neither can detect hydrogen. Hope this is of some help to you.
Best regards,
BBN
There is no reliable substitute for a CHN analyzer. However, in addition to the EDX/XPS analyses suggested by Mr. Nyakuma (which will provide CNS and O but not H), you can get a reasonable estimate by correlating heating values to O:C and H:C ratios if you have some reasonably similar fuels. You can then use the heating value to estimate these ratios and, assuming nothing else exists in the fuel, calculate the composition. This technique will not be reliable for N or S since they are such minor components of the fuel. You should use heating values and O:C/H:C data all calculated on a dry, ash-free basis.
In view of biomass analysis, before the widely available CHN analyzer, C could be analyzed using a TOC (total organic carbon) analyzer with proper digestion and preparation of your biomass samples. For N, Kjeldahl Method or Kjeldahl Digestion could be done to determine the amount of organic nitrogen in the form of ammonia. Sulfur on the other hand may be determined using the Eshka method or via bomb calorimetry followed by precipitation of the sulfur with barium chloride. as for O and H, these may have to be determined via correlations as suggested by Mr. Larry Baxter or perhaps via Orsat analysis under controlled conditions and complete combustion.
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