Background and Technology:
Gas Chromatography (GC)
Gas Chromatography is a technique that allows us to identify the compounds of a sample through two phases: the moving phase and the stationary phase. The sample is injected into the instrument and vaporized in the injector using an inert carrier gas as the mobile phase, and it will move through a glass capillary column lined with a high molecular weight liquid as the stationary phase. A detector quantifies the various components as they emerge and generates a chromatogram.
Mass Spectrometry (MS)
Mass Spectrometry is a technique used to identify the composition and structure of a compound. The material is fragmented and are separated according to their mass-to-charge ratios (m/z). The type of mass analyzer is used to describe the mass spectrometer, and while there are several different types, the types utilized at Armstrong Forensic Laboratory are called Quadrupole and Ion Trap. A detector collects the ions that have been produced and generates a ‘spectrum’ of the different masses.
While the gas chromatograph can successfully separate and individual components of a sample, it fails to reliably identify the specific analyte. Conversely, the mass spectrometer can identify the specific analyte, and it produces quantitative results. When used in conjunction with each other, the result is a more accurate, reliable and quality analysis of the sample. This is why using a combination Gas Chromatography Mass Spectrometry instrument is utilized for component identification and quantification at Armstrong Forensic Laboratory. Our goal is to provide quality, court-ready data for our clients.
Ion Trap VS Quadrupole
Armstrong utilizes both Ion Trap and a Quadrupole mass analyzers. There are both advantages and disadvantages to each machine. While they are both compact in size, are capable of fast scan rates, the Ion Trap tends to be more sensitive. A more sensitive machine means it can measure smaller peaks more accurately. Also, the Ion Trap does not have a separate ion source like the Quadrupole, which requires regular cleaning, so ions are not lost between the ionization chamber and the analyzer. Both types of machines are used in our lab every day, and both produce accurate, reliable, court-ready analyses to our clients. The picture in the header of this page is of our newest Quadrupole Mass Analyzer, and the one pictured below is one of our Ion Trap Mass Analyzer.
- Drug Identification
- Ignitable Liquids ASTM 1618
- Product Testing CPSC Phthalates
- Volatiles EPA
- Semi-Volatiles EPA
- Air Quality EPA