Premium
Fast GC—MS in Supersonic Molecular Beams
Author(s) -
Amirav Aviv,
Dagan Shai
Publication year - 1997
Publication title -
israel journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.908
H-Index - 54
eISSN - 1869-5868
pISSN - 0021-2148
DOI - 10.1002/ijch.199700053
Subject(s) - chemistry , electron ionization , mass spectrometry , selectivity , ionization , analytical chemistry (journal) , chromatography , chemical ionization , gas chromatography , supersonic speed , ion , organic chemistry , physics , thermodynamics , catalysis
Abstract 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 vibrationally 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.