I have used potassium dichromate method to find organic matter of contaminated soil, but the results are not satisfactory, is there any other method available, or any specific method to find organic matter in soil contaminated with petroleum waste?
If your targeted organic matter in question are different than hydrocarbons contained in petroleum, you can opt solvent extraction (methanol, ACN and water) for polar organics. It is also important as to which analytical method you wish to employ for estimating organic contents of the soil.