TOC, Total Organic Carbon, the most important to the geological study, even any other soil science, or other studies. TOC is usually calculated to normalize the sample organic matter to eliminate other foreign organic matter which had been added later. To understand the accurate organic matter contained we need to normalize the samples by TOC (wt%). However, in the organic geochemical study, we can use Phenanthrene instead of TOC. But, to normalize the sample TOC is well accepted among the geoscientists.
Let’s do How to Calculate the TOC?
Suppose, From a 3000mg of the rock sample, we need to do an acid treatment to remove all the inorganic Carbon from the sample. After the acid treatment, Now, the sample contains only organic carbon. Because acid treatment (Adding HCL and/or HF acid) cannot remove the organic carbon. Then, we need to dry and weight the acid treated sample. And now, It will be in a powder form.
Now, we have a 124 mg of acid treated powdered sedimentary rock samples from the 3000mg of rocks to measure for the geochemical study. From this 124mg amount, we need to take 6.00 mg for the “Elemental Analyser” machine to measure TOC. Make a rolling ball type with this 6.0 mg of powdered sample with an aluminum foil paper and use in the Elemental analyzer machine.
Suppose, After Elemental analyzer machine, we found 0.043mg of organic carbon (C). Then, Calculate for the whole rock sample, how much Organic Carbon (C) contains.
The calculation is;
6.00 mg of powder sample contains 0.043 mg of Organic carbon
so, 124mg of Powder sample contains (0.043mg*6.0mg)/124mg
=0.0020 mg of Organic Carbon (C)
As 124 mg of acid treated sample, we found from the 3000 mg of a whole rock sample. So, 3000mg of the whole sample also contains this 0.0020 mg of Organic carbon.
Now, The Total Organic Carbon percentage is
= 0.02% of TOC (wt%).