Method for quantifying the pyrogenic carbon present in a sample of an organo-mineral or mineral matrix comprising charcoal and/or biochar

A process for quantifying pyrogenic carbon content present in a sample comprising an organo-mineral and a mineral matrix, charcoal and biochar comprising:

• A) heating the sample under an inert atmosphere according to a first temperature sequence, with an initial temperature of between 10° and 300° C., and a final temperature of between 50° and 800° C.;
• B) heating a residue of the sample resulting from the heating under an inert atmosphere under an oxidizing atmosphere according to a second temperature sequence with an initial temperature of between 10° and 300° C., and a final temperature of between 70° and 1000° C., the second temperature sequence comprising at least one thermal gradient between 1° C./min and 50° C./min, and measuring at least one amount of CO2 released during the second temperature sequence;
• C) starting, with at least one of a curve representing an evolution as a function of temperature of an amount of CO2 released during the heating under an oxidizing atmosphere, applying a Gaussian deconvolution to the curve for determining a first and a second Gaussian centered, respectively, on a first and a second temperature, the first temperature being between 380° C. and 540° C., and the second temperature being between 500° C. and 600° C.;
• and
• D) from surface areas of the first and second Gaussians, determining pyrogenic carbon content X3 present in the sample with the pyrogenic carbon determined according to a formula:
• X
• 3
• =
• X
• 2
• -
• A
• ·
• X
• 1
• 1
• +
• A
• ·
• B
• in which X1 and X2 are carbon contents determined respectively from surface areas of the first and second Gaussians, A is a coefficient representing a proportion of the mineral matrix in the second Gaussian relative to the first Gaussian, and B is a coefficient representing a proportion of at least one of the charcoal and the biochar in the first Gaussian relative to the second Gaussian.