According to our textbook, mass spectrometry is a specific test used to identify a drug substance (Saferstein, 2020). This test is preceded by other tests that should rule out the possibility of a multitude of drugs. The test must confirm any probability of another substance that may respond identically to the scheme of the selected tests (Saferstein, 2020). The tester has to be able to rule out the ability of any other substance reacting the exact way that the suspected drug would to the specific test in order to have a positive identification of the drug. The positive identification of the suspected drug is important, and if not properly identified could lead to further scrutiny of the test conducted to identify. The test will first begin with the screening process to attempt to narrow down his or her possibilities of pinpointing the suspected drug. The screening test is the first step in analyzing a drug and is extremely important in the identification process. A screening test reduces the possibilities of the drug to a small and manageable number (Saferstein, 2020). The screening test can have either positive or negative results. The negative results are important as they still help in narrowing down the suspected substances. Once the screening test is completed, the test can then take their results and continue testing their positive results. The test will then move to the second phase of their analysis, which is the confirmation (Saferstein, 2020). The confirmation takes the positive results and involves further testing and this is the phase that a specific test like mass spectrometry comes into play. A test like mass spectrometry allows the test to make a positive identification of their suspected drug. Mass spectrometry is considered to be the golden analytical tool because of its ability to characterize direct molecular structural information of applicable analyte molecules (Habib et al., 2021).
Habib, A., Bi, L., Hong, H., and Wen, L. (2021). Challenges and Strategies of Chemical Analysis of Drugs of Abuse and Explosives by Mass Spectrometry. Frontiers in Chemistry, NA. https://link.gale.com/apps/doc/A648928241/AONE?u=tel_a_bethelc&sid=AONE&xid=fb5431ee
Saferstein R., Roy T. (2020). Criminalistics. [Savant Learning Systems]. Retrieved from https://savantlearningsystems.vitalsource.com/#/books/9780135268407/
The Mass Spectrometry Process
Saferstein (2015) reports that because of its ability to separate components of complex mixtures, the gas chromatograph (GC) is one of the most critical tools in a crime laboratory. However, the GC has a significant drawback in that it cannot produce a specific identification of the separated components. That is, when a GC reports a particular time of retention of a substance, the forensic scientist cannot produce specific identification with certainty.
That problem can be solved mainly by coupling the GC with a mass spectrometer. In this process, a direct connection is made between the GC and the spectrometer. When the GC separates the components, each component is then allowed to flow into the spectrometer directly from the GC. Silverstein (2015) states that when the components enter the mass spectrometer, they go into a high-vacuum chamber where a beam of high-energy electrons bombards them. When the electrons collide with the molecules, the molecules lose their electrons, giving them a positive charge. These charged molecules (called ions) are unstable and decompos quicklye into small fragments. When the fragments pass through a magnetic field, they are separated by mass. This fragmentation serves as a fingerprint of the material being examined as no two elements have the same fragmentation pattern.
Visotin and Lennard (2016) describe a use for the mass spectrometer in solving arson crimes. One of the problems of showing arson is the ability to detect liquid residues at the scene. A new mass spectrometer known as the TRIDON-9 uses solid phase micro-extraction as the sampling method. Visotin and Lennard (2016) tested the spectrometer with the four flammable liquids of mineral turpentine, diesel, gasoline, and kerosene. They also tested seven substrates (wool carpet, nylon, mineral turpentine, polypropylene, polyurethane, untreated pine, and foam underlay). The TRIDON-9 correctly classified the majority of samples analyzed. The researchers believe this is a significant step forward in arson detection.
Saferstein, R. (2015). Criminalistics: An introduction to forensic science (11th ed.). Pearson.
Visotin, A., Lennard, C. (2016). Preliminary evaluation of a next-generation portable gas chromatograph mass spectrometer (GC-MS) for the on-site analysis of ignitable residue liquids. Australian Journal of Forensic Sciences, 48(2), 203-221. https://doi-org.bethelu.idm.oclc.org/10.1080/00450618.2015.1045554