It was a question asked to me by my boss. Is there a general method used? By the way, they plan to test TPH (Total Petroleum Hydrocarbons) using a a Gas Chromatograph. If there's only one method could you elaborate as much as possible, from sample collection, equipment necessary, extraction procedure(s), and anything else. If various, no need to explain, some links would be great. I think they're serious about doing this and I want to spearhead it. Thanks a many