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5.1: GC-MS Pre-lab Assignment

  • Page ID
    408576
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    What is in your pocket? If you have paper currency in your pocket, it is likely that you are carrying trace amounts of illicit drugs, including cocaine. Several studies have shown that about 80% of U.S. dollar bills are contaminated with cocaine. In this experiment, you will use Gas Chromatography-Mass Spectrometry (GC-MS) to perform forensic analysis on money, and quantitate the amount of cocaine on bills.

    Pre-Lab Assignment

    1. Read the entire contents of this module
    2. Use Web of Science or another literature database to find the article below and read it. You will use a GC-MS method based largely on this paper. Be on the lookout for the ions they focused on in single ion monitoring (SIM) mode for cocaine and the doxepin internal standard. You will also use doxepin as an internal standard:
      • Negrusz, A.; Perry, J. L.; Moore, C. M. J. Forensic Sci. 1998, 43 (3), 626.

    3. Use Web of Science or another literature database to research cocaine and other substances that might be found on money. Make a prediction about what you might look for on your bills during this experiment.
    4. Answer the pre-lab questions below.
    5. This experiment gives you the opportunity to analyze your own money if you wish. If you want to bring in your own bills, please do so. (Foreign Bills are welcome!)

    Pre-Lab Questions:

    1. Draw the structures of cocaine and doxepin and give their molecular masses.
    2. Use an internet search to find the Mass Spectrum of cocaine and doxepin. What is(are) the most abundant ion(s) in each case?
    3. Predict at least one other compounds that might be present in your dollar extracts. Also find their masses and determine likely fragments that will appear in their MS. You can find mass spectra for many substances here: https://webbook.nist.gov/chemistry/
    4. Describe the effect of a gradient temperature program compared to isothermal gas chromatography.
    5. List the settings for the GC and MS found in the Negrusz paper.

    Sources:

    https://en.wikipedia.org/wiki/Contaminated_currency


    5.1: GC-MS Pre-lab Assignment is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.