Cu+ chemical ionization for analysis of hydrocarbons by gas chromatography/mass spectrometry

The use of copper ions for chemical ionization (CI) coupled with gas chromatography/mass spectrometry (GC/MS) of hydrocarbons is reported. Cu⁺–CI was performed in a high-pressure, fast atom bombardment ion source coupled with both a gas chromatograph and a mass spectrometer. The suitability of the Cu⁺–CI method is illustrated by the analysis of pure alkylbenzenes, alkylthiophenes, octenes, and by the analysis of a light mixture of aromatic hydrocarbons. The Cu⁺–CI/GC mass spectra display an abundant [M+⁶³Cu]⁺ ion, together with fragmentations, that are of structural interest. The detection limit for isobutylbenzene, taken as model compound, is 100 times lower than that for electron ionization.