I need to dissolve a caffeine pill in grapefruit juice, do an experiment (which is irrelevant to my question), and then extract the caffeine somehow so it can be massed. I've tried using coffee filters, but the accuracy is too low. Is there any chemical substance that is mostly insoluble to grapefruit juice, but is a solvent to caffeine, that I could use to alienate the caffeine? Any other suggestions that I'm not thinking of that are quicker than evaporation, or would speed up evaporation?
Thanks!