Ear syringe pipetting bulb

Ear Syringe Pipetting Bulb. The recent article by W. E. Harris and B. Kratoehvilldiscussed some of the common problems students in beginning analytica...
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Ear Syringe Pipetting Bulb The recent article by W. E. Harris and B. Kratoehvilldiscussed some of the common problems students in beginning analytical laboratories encounter. One that had puzzled me for some time was how t o get the students t o use a pipet bulb with pipets of larger or smaller diameter than the opening in the bulb. They invariably insist on inserting the pipet into the bulh. In the awkward process of trying t o lift the solution or remove the bulb prior to transfer, they have been known to tip volumetric flasks or chip the tips of the pipets because the bulb did not fit. The authors suggested adding a flared end to the bulb. Recently I purchased some 2-oz. ear syringes tobe used as pipet bulbs. Instead of fitting around the pipet, they fit inside the opening a t the top. The taper on the point makes them general for all sizes of pipets. Students prefer the syringes over the "real" pipet bulb because they are easily removed from the pipet. I prefer them because they save on ancillary glassware, are easy t o use and cost much less than "real" pipet bulbs. 'Harris, W. E., and Kratochvil, B., J. CHEM. EDUC., 53,253 (1976). University of Arkansas a t Little Rock Little Rock. 72204

434 1 Journal of Chemical Education

Richard H. Hanson