Introduction to Soil Chemistry

192 chromatography
sufficient. True identification occurs when HPLC and GC are coupled to a
spectrophotometic method such as MS and/or UV–Vis.
PROBLEMS
9.1. Explain how all chromatographic methods are similar.
9.2. Explain how the basic chromatographic methods are different.
9.3. What physical characteristics must components have to be separated by
gas chromatography?
9.4. What do the terms Rf and Rt refer to? Explain how they are used in
determining what components are likely to be present in a mixture.
9.5. Describe detection methods used in GC, HPLC, and TLC.
9.6. What general characteristic must a component have to be separated by
electrophoresis?
9.7. How are soil thin-layer plates used in environmental investigations?
9.8. Explain why it is advantageous to have separated compounds exiting a
GC or HPLC column analyzed by MS.
9.9. What is the difference between the mobile phase and the stationary
phase in chromatography?
9.10. The chromatograms from two different injections have the following
components (peaks) with the indicated retention times. Injection 1: peak
1, Rt = 0.55; peak 2, Rt = 1.25; peak 3, Rt = 2.44; peak 4, Rt = 5.65. Injection
2: peak 1, Rt = 0.22; peak 2, Rt = 1.00; peak 3, Rt = 5.65; peak 4,
Rt = 6.74. Which of the peaks in the two chromatograms is likely to be
the same compound?
BIBLIOGRAPHY
Ardrey RE. Liquid Chromatography–Mass Spectrometry: An Introduction. New York:
Wiley, 2003.
Grob RL, Barry EF. Modern Practice of Gas Chromatography. New York: Wiley-
Interscience, 1995.
Niessen WMA (ed.). Current Practice of Gas Chromatography–Mass Spectroscopy.
New York: Marcel Dekker, 2001.
Snyder LR, Kirkland JJ, Glajch JL. Practical HPLC Method Development, 2nd ed.
New York: Wiley-Interscience, 1997.
Tabatabai MA, Frankenberger WT Jr. Liquid chromatography. In Methods of Soil
Analysis, Part 3: Chemical Methods, Bartels JM (ed.). Madison, WI: Soil Science
Society of America, American Siociety of Agronomy, pp. 225–245, 1996.