A Modified Adapter for Liquid Transfer In the course of daily laboratory work, liquids of varying viscosities must often be quantitatively transferred between two flasks. This frequently proves difficult or tedious using standard techniques. Pasteur pipets, with a volume of approximately 2 mL, are seldom practical for volumes greater than 20 mL and are difficult touse with low-boiling solvents and viscous fluids. Cannulas, used in conjunction with a positive nitrogen pressure, are plagued by stopper blowout and, for this reason,are limited to nonviscous liquids. We wish to describe, here, a Pyrex and Teflon apuaratus for liauid transfer using an aspirator vacuum.
The adapter, which is easily fabricated from Pyrex tubing and a common T 14/20 or T 24/40 ground glass joint, is depicted on the left. The Teflon tubing (1/18-in.id., 'I8-in. ad., '182-in. wall thickness, Cole Parmer # R-6406-62) was selected for its flexibility, inertness, and thermal stability. The apparatus is assembled by inserting this tubing into the glass inlet of the adapter; flaring of the inlet and warming of the glass facilitates this operation. Once the Teflon has conformed t o the internal diameter (-3132-in.) of the adapter inlet, i t can he removed, cleaned, and reinserted while maintaining a snug fit. The straight glass inlet maximizes strength and simplifies construction, and we feel that the Tefloninsert design is superior t o the commercially available version (Ace # 5175) for drawing liquids under reduced pressures. The apparatus has been found to serve equally well far transferring voltatile isopentane solutions and heavy oils such as glycerol. In all cases, the adapter permitted transfer with no spillageand a minimum of added rinse solvent. An illustration of the liquid transfer adapter in operation is given on the right. Richard A. Bunce and M. Wayne Adkins Oklahoma State University Stillwater. OK 74078
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Journal of Chemical Education
