All that I could suggest might be a silica-based absorber, which may or may not tie up hydrocarbons. The desiccant might be the same one that you use in the lab. It would probably be clay, silica gel, or activated alumina. There is a finite capacity, and a quick web search revealed several companies manufacturing desiccants which turn a color when they are exhausted. A quick call to one of their tech services might be helpful. A desiccant vendor I called recommended a 3A or a 4A molecular sieve to trap water but not hydrocarbons. I don't know how well that would work. They also suggested silica gel. So it's your choice.

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