The Biogenic Interference Calculation (BIC) for Delineating Petroleum Hydrocarbons in Organic Soils and Compost has a definition for what classifies an organic, peat or compost soil by looking at the Total Organic Carbon (TOC) percent (%). However, the guide does not indicate which TOC in soil test to analyze.
Bureau Veritas can complete TOC by Titration or a TOC by Combustion (sometimes referred to as TOC by LECO).
TOC by Combustion (also TOC by LECO) would be the preferred method.
The only differential factor of some significance is the potential interference of Fe(II) in the TOC titration analysis. With peat bogs, or any highly saturated soil, there could be elevated levels of Fe(II) compared with more standard soil types. That said, if TOC titration had been selected in the past that would be acceptable, as the TOC content of any highly organic soil would diminish any potential Fe(II) positive bias.