Integration of Capillary Column Gas Chromatography into Project-Oriented Laboratories

Carleton College, Northfield MN

Investigators

Abstract

Chemistry (12) Capillary column gas chromatography (GC) is integrated into several courses that offer multi-week, collaborative, project-oriented laboratory experiences, using experiments which are adapted from standard literature. The Chemistry Department currently offers many of these types of laboratory experiences to students, but feel the addition of several capillary column GC's would greatly enhance the range of projects that could be offered. The Department greatly values multi-week, collaborative, project-oriented laboratories because the skills students develop, such as working as a member of a team, designing experiments, and evaluating data, are central to being a scientist. In addition, offering multi-week projects, which closely parallel a true research experience, inspires more students to seek out undergraduate research experiences. Capillary column GC is a flexible, fast, and quantitative tool that can support many types of projects in introductory, environmental, and organic chemistry. The GC instruments have temperature programming capabilities and are equipped with two detectors, two columns, and an integrator for each instrument. The majority of the GC instruments have flame ionization detectors; however, two of the instruments are each equipped with an electron capture detector. The addition of two electron capture detectors allows two of the GC instruments to support project-oriented laboratories in environmental chemistry courses where the selective detection of halogenated and nitro-substituted compounds, a typical motif for many pesticides and herbicides, are crucial. The majority of the capillary column GC usage occurs in sophomore organic chemistry laboratories where there has been a shift in curricular focus to offering all project-oriented laboratory experiences. Some examples of projects to be offered include the examination of competitive reaction pathways in the dehydration reaction of an alcohol, a study of structure/reactivity relationships in the Diels-Alder reaction, and the examination of the enantioselective reduction of an acylnaphthalene derivative. Introductory and environmental chemistry courses at Carleton offer at least one multi-week, project oriented laboratory experience. During this period students usually pick from a menu of possible projects that a team can undertake. In introductory chemistry three projects take advantage of the new capillary column GC's. These projects include an examination of intermolecular forces in several liquids, the investigation of a simulated forensic arson sample, and the investigation of the volatility of fluorinated metal-acetylacetonate complexes. In environmental chemistry a project would call for a student group to examine the distribution of a herbicide in either soil or water in the immediate region around the campus. An additional project is also used to examine pesticides and herbicides in commercially grown fruits and vegetables.