|FIALKOV, ALEXANDER - Tel Aviv University|
|AMIRAV, AVIV - Tel Aviv University|
Submitted to: Journal of Chromatography A
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/5/2019
Publication Date: 11/6/2019
Citation: Fialkov, A.B., Lehotay, S.J., Amirav, A. 2019. Less than 1 minute low-pressure gas chromatography - mass spectrometry. Journal of Chromatography A. 1612 (2020) 460691. https://doi.org/10.1016/j.chroma.2019.460691.
Interpretive Summary: Gas chromatography with mass spectrometry (GC-MS) is one of the most common instrumental tools in analytical chemistry, which is used for detection of millions of possible chemicals in countless types of samples and applications. Conventionally, GC-MS takes about 30 minutes per sample analysis conducted sequentially, thus a typical batch of 40 samples requires nearly a full day before the results can be obtained. Using the novel, fast GC-MS approach described in this study, analysis time takes merely 1 minute or less, and several example applications were demonstrated using the approach. The fast GC-MS device used is commercially viable as an add-on to existing GC-MS instruments, and if successfully marketed and widely implemented, the approach has the potential to revolutionize GC-MS analysis in many common applications, including analysis of chemical residues in foods.
Technical Abstract: Conventional gas chromatography- mass spectrometry (GC-MS) takes 20-40 min per sample, which is undesirably slow in any application if speed can be increased while still meeting analytical needs. In this study, we achieved reasonably good separations with full analysis cycle times of less than 1 min by combining for the first time low-pressure (LP) GC-MS with low thermal mass (LTM) resistive-heating of the capillary column for rapid temperature ramping and cooling. The analytical column is threaded into the LTM thin-walled metal tubing in an instrumental device known as “LTM Fast GC” that is mounted at the top of the gas chromatograph in a detector port. The column inlet and outlet are connected to the GC injector and MS transfer line as usual. For LPGC-MS, a 40 cm, 0.1 mm. i.d. uncoated flow restrictor capillary connected at the injector is coupled with a 2.5 m, 0.25 mm i.d., 0.25 µm film thickness analytical column leading to the MS. Thus, the inlet operates at normal GC pressures, but the analytical column is under vacuum, which increases the optimal helium carrier gas flow velocity thereby increasing speed of full range separations while maintaining acceptable quality of chromatography. This column configuration in LTM-LPGC-MS trades a 64-fold gain in speed of analysis vs. standard GC-MS for a 4-fold loss in chromatographic peak capacity, thereby converting analysis time from minutes into seconds in common applications. For example, jet fuel containing fatty acid methyl esters (akin to biofuel) was separated in 25 s with < 1 min full analysis cycle time. An EPA Method 8270 mixture of 76 analytes was also analyzed in < 1 min full cycle time by LTM-LPGC-MS. In this report, we describe and discuss the several advantageous and practical features of LTM-LPGC-MS, as well as its trade-offs.