Evaporate carefully on warm H,0 bath under hood until solvent is reduced to ca 5 mL. Transfer to 15 mL graduated centrifuge tube with small amounts solvent, add small boiling chip, and immerse tube in warm H,O to remove solvent. When solvent is reduced to 0.5 mL, transfer tube to beaker containing acetone and ice, and let vanillin precipitate. When upper layer is clear, transfer this solution to small container with Teflon cap or liner, using syringe or glass tube drawn out to capillary tip at one end. If desired,this solution can be further concentrated to ca 0.2 mL.Chromatograph as soon as possible after concentrating. Do not let concentrate remain overnight before chromatography.