Fast GC-MS in supersonic molecular beams

Aviv Amirav*, Shai Dagan

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The features of supersonic molecular beams (SMB) are used to improve gas chromatography-mass spectrometry (GC-MS) performance and establish a new method of fast GC-MS. In SMB, the sample compounds are vibrationals cooled such that their electron impact mass spectra are characterized by enhanced M+ peaks, together with library-searchable fragments. A new ionization method, hyperthermal surface ionization (HSI), provides ultrasensitive ionization coupled with a tunable degree of selectivity for nitrogen-containing drugs. SMB enables the use of very high carrier gas flow rates which, when a short megabore column is used, results in ultra-fast GC-MS having conventional chromatographic peak widths. Thus, fast GC-MS in SMB can be performed with conventional quadrupole analyzers. The slightly reduced GC resolution can, in many cases, be compensated for by the selectivity of hyperthermal surface ionization or by the increased EI selectivity through enhanced M+. "Fast", "very-fast", and "ultra-fast" GC-MS are defined and demonstrated with drugs, and the ability to analyze underivatized steroids is shown. Practical examples are shown including ultra-fast GC-MS of lidocaine in human plasma extract achieved in a few seconds and screening of other drugs, without any sample preparation or extraction, achieved in less than three minutes. We conclude that GC-SMB-MS exhibits a combination of faster analysis with improved sensitivity and selectivity, a wider range of molecules amenable to GC-MS, improved MS information, and higher a degree of flexibility.

Original languageEnglish
Pages (from-to)475-482
Number of pages8
JournalIsrael Journal of Chemistry
Issue number4
StatePublished - 1997


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