Biology Questions

1. What are some of the advantages and disadvantages to using gas chromatography for the analysis of forensic and/or pharmaceutical samples?

2. A gas chromatogram of a sample shows several peaks that appear very close to each other. How would you determine that each peak results from a single compound? In other words, how do you show that there are no overlapping or co-eluting compounds?

3. The research paper, "(2S)-1-(4-Methoxyphenyl)-N[1(1R)-2(-4-methoxyphenyl-1-methylethyl]2-proanamine in crude p-methoxyamphetamine (PMA) produced by the Leuckart Method" by D. Blachut, et al., Z. Naturforsch. 57b, 593-97 (2002). This paper shows a variety of techniques, TLC, GC, MS, x-ray crystallography may be required to truly identify unknown compounds. Figure 4 shows the gas chromatograms of the crude reaction mixture. Note that peaks 4 and 5 are enantiomer-compounds that are mirror images of each other and very difficult to separate on a GC column. Is the resolution between these two peaks sufficient for quantitative studies if they are needed? How about the resolution between peaks 2 and 3? Can these compounds be successfully quantified?

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1. What are some of the advantages and disadvantages to using gas chromatography for the analysis of forensic and/or pharmaceutical samples? The main advantage of gas chromatography for use in forensic and/or pharmaceutical samples is the ability to separate various mixtures into their respective individual components. They can then be analyzed one at a time. The separation is based on the mixtures’ affinities for each of the two phases of gas chromatography. The main disadvantage in this would be the fact that a mixture cannot always be entirely separated. Sometimes, there will be compounds that reach the end point of the column at the same time. This “co-elution” causes a difficulty in the ability to measure a specific component and, therefore, another form of testing would be needed....