Up to date, the fiber optic sensor seems to be the most useful for my needs. However, the GC seems to give more precise measures which could be given as a plus.
However I have one question. I was talking with a chemist and he said they use to detect hydrocarbons with some sort of chemical, sugar and some color dye. The darkness of the color dye would determine the amount of hydrocarbons within the soil. Anyone know which chemical this could be? I almost seem to believe this is a old folk story because he says he "forgot" how they did it. However he said he had 2 small jars of this mixed substance left. He offered to give them to me. Perhaps this could be used to duplicate, or learn from. Please let me know your inputs.