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ERIC Number: EJ927045
Record Type: Journal
Publication Date: 2011-Apr
Pages: 2
Abstractor: As Provided
Reference Count: 4
ISSN: ISSN-0021-9584
Design for a Simple and Inexpensive Cylinder-within-a-Cylinder Gradient Maker for the Undergraduate Biochemistry Laboratory
Sims, Paul A.; O'Mealey, Gary B.; Khan, Nabeel A.; Larabee, Chelsea M.
Journal of Chemical Education, v88 n4 p508-509 Apr 2011
A design for a simple and inexpensive gradient maker is described. The gradient maker is assembled by (i) cutting the tops off two plastic bottles of differing diameters to produce two cylinders with intact bottoms; (ii) drilling a small hole toward the bottom of the smaller diameter cylinder and plugging the hole with a size 00 cork stopper; and (iii) placing the smaller diameter cylinder within the larger diameter cylinder and holding in place with epoxy. Removal of the cork stopper connects the inner and outer chambers, and two lengths of glass tubes, joined by a length of flexible plastic tubing, connect the inner chamber and the environment. The resulting cylinder-within-a-cylinder design is compact and can easily fit on a small magnetic stirrer, and conductivity tests showed that the gradient produced is linear. The cost is low enough that many units can be assembled and used in the undergraduate laboratory for less than the price of a single commercial unit. (Contains 1 figure and 3 notes.)
Division of Chemical Education, Inc and ACS Publications Division of the American Chemical Society. 1155 Sixteenth Street NW, Washington, DC 20036. Tel: 800-227-5558; Tel: 202-872-4600; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A