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Drop Counter as Fraction Collector

Drop Counter as Fraction Collector

Although the Drop Counter was developed to record drops during titration, attaching the Luer-lock stopcock to the outlet of a chromatography column adapts it for use as an inexpensive fraction collector for column chromatography. Although column chromatography is an essential part of the undergraduate biochemistry laboratory curriculum, most undergraduate programs cannot afford to purchase a class set of fraction collectors, and many protocols call for the students to collect each fraction into a graduated cylinder.

An article published in the September 2008 issue of the Journal of Chemical Education, (Nash, B.T. (2008) J. Chem. Ed. 85:1260), describes the use of the Vernier Drop Counter as a fraction collector. Although test tubes containing the fractions must be moved manually, this protocol gives students the opportunity to learn the essential skills needed to operate a computer-interfaced fraction collector (aligning the sensor with the column outlet and test tube, calibrating the drop size, and operating software).

Although the experiment file was written for a non-interfaced spectrophotometer, PC users can perform this experiment with an Ocean Optics spectrophotometer by opening two Logger Pro windows.

Profile for gel filtration chromatography
Profile for gel filtration chromatography

Download the Logger Pro experiment file »

Supporting material, including student handouts, notes for the instructor, and answers to a post-lab problem set are available for download at JCE Online at www.jce.divched.org/Journal/Issues/2008/Sep/abs1260.html

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