What do you mean "a very small amount" ?...100 mg, 10 mg or 1 mg? I would like to recommend you a book "Mircoscale Organic Laboratory" D.W.Mayo, R.M.Pike, D.C.Forbes, Wiley, 2011. You will find there a lot of techniques dealing with a small quantities of materials. I usually perform such tests in small vials ( 5mm width-5cm lenght). After test I evaporate solvent (sand bath or hair dryer) and do next test with another solvent.
What do you mean "a very small amount" ?...100 mg, 10 mg or 1 mg? I would like to recommend you a book "Mircoscale Organic Laboratory" D.W.Mayo, R.M.Pike, D.C.Forbes, Wiley, 2011. You will find there a lot of techniques dealing with a small quantities of materials. I usually perform such tests in small vials ( 5mm width-5cm lenght). After test I evaporate solvent (sand bath or hair dryer) and do next test with another solvent.