If You Were a Molecule in a Chromatography Column, What Would You See?

John Mattice
Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR 72704
J. Chem. Educ., 2008, 85 (7), p 925
DOI: 10.1021/ed085p925
Publication Date (Web): July 1, 2008

Abstract

To visualize what takes place in a chromatography column, enlarge the molecules to human size and expand the columns to keep the ratio of size of molecule to size of column the same. If we were molecules, what would the columns be like? A typical gas chromatography (GC) capillary column would be 50 x 106 km (31 million mi) long, have a diameter of 420 km (260 mi), and have a stationary phase thickness of 420 m (a quarter of a mile). A typical high performance liquid chromatography (HPLC) column would be 3300 km (2000 mi) wide and longer than the distance from the earth to the moon. It would be packed with particles the size of Mt. Everest with a bonded stationary phase a little less than 4 m (12 to 13 ft) deep. Using this system, we explain how band broadening occurs as a result of resistance to mass transfer, multiple flow paths, and stagnant mobile phase.

Keywords (Audience):

High School / Introductory Chemistry

Keywords (Domain):

Analytical Chemistry

Keywords (Pedagogy):

Analogies / Transfer

Keywords (Subject):

Chromatography
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History

  • Received: August 03, 2009

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