Inexpensive Pipet Delivery Device To prevent possible injury when pipetting solutions, students are generally not permitted to use the mouth for suction. The use of an inexpensive rubber pipet bulb of 1or 2 oz volume is often recommended t o provide the necessarysuctian for this laboratory operation. Our experience has shown that most students find it difficult to remove simultaneously the rubber bulb from the pipet after a solution has been drawn into it and to cover the top of the pipet with the index fmger. We have found that this operation may be greatly facilitated by inserting the tapered end of a perforated 1.5 ml polypropylene Eppendorf micro test tube into the open end of the rubber pipet bulb. A small perforation of the desired dimension may easily be made in the micro test tube by heating an unfolded paper clip (held with pliers) to redness usinga Bunsen burner and pushing it quickly through the tapered end of the test tube. With the perforated tube inserted in the rubber hulh, the student may then press the tap of the pipet gently against the inner wall of the test tube while drawing solution into the pipet using suction produced by the rubber bulb. When the desired solution height has been reached, the delivery device (bulb and test tube) can easily and quickly he removed and the index finger placed on the top of the pipet in preparation for the final step in the delivery of an accurately measured volume of solution. This inexpensive device accommodates most sizes of delivery pipets. Adelhert M. Knevel Professor of Medicinal Chemistry School of Pharmacy & Pharmacal Sciences P u r d u e University West Lafayette, IN 47907
Volume 57. Number 4, April 1980 / 285
