A laser plasma ion source was used to ionize volatile organic compounds in a gas sample. The plasma was generated on a metal target in the intermediate vacuum region of ~0.3 Torr using a pulsed Nd:YAG laser with a wavelength of 1 μm. The resulting ions mass spectra were acquired using orthogonal time-of-flight mass spectrometer (O-TOF MS). When using a copper target, the ions formed are simple complexes (CuM+ ) of copper ions with organic molecules. The possibility of online identification of trace amounts of alkanes in nitrogen and air, with a detection limit of ~10 ppb, was demonstrated. The ionization efficiency of volatile organic compounds through the formation of clusters with metal ions is 10-4 in terms of the quasimolecular complex ions. The rate constants of ion-molecular reactions of copper ions with octane and water molecules in nitrogen and air are estimated.
Keywords: Cu; complex; ionization; octane; rate constant.
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