The fragmentation of the cluster ion, [A1῎HCl῎A2῎H] ῌ of amine bases A1 and A2, is studied by the BEBE type tandem mass spectrometer. The cluster ion, [A1῎HCl῎A2῎H] ῌ , is generated by the fast atom bombardment (FAB) ionization of mixture of two hydrochlorides of amines. The precursor ion is selected by the first analyzer (BE) and the product ions are scanned by the second analyzer (B/E linked scanning). ῌ are found to be related to their relative proton a$nities and are used to determine the proton a$nities (PAs) of methamphetamine and its analogs. The PA of methamphetamine is estimated to be 965 kJ/mol.
IntroductionMethamphetamine is the most commonly abused of this class of drugs in both the United States and Japan. In some European countries there is a greater problem with abuse of amphetamine and/or the synthetic analogs: 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxymethamphetamine (MDMA), and 3,4-methylenedioxy-N-ethylamphetamine (MDEA), they are often seized by the law enforcement agencies in Japan these days.Mass spectrometry, and in particular gas chromatography/mass spectrometry (GC/MS), is being extensively used for the detection and analysis of drugs of abuse and their metabolites in body fluids. The ionization method for GC/MS is mostly electron ionization (EI), however, chemical ionization (CI) is often used to confirm the molecular weight. In recent years, liquid chromatography/mass spectrometry (LC/MS) using atmospheric pressure chemical ionization (APCI) or electrospray ionization (ESI) method has become one of the important techniques for trace analysis of drugs of abuse. In CI, APCI, and even in ESI, analyte charging in the gas phase occurs through gas-phase protontransfer reactions. Therefore, the measurements of proton a$nity (PA) values of drugs of abuse seem to be more interesting. The proton a$nities (PAs) of many compounds have been measured and reported. 1), 2) Cardoso et al. recently reported the PAs of some phenylalk-
ῌῌ910῍8507
3῍9῍1῍Natural Science Education Laboratory, Faculty of Education and Regional Studies, Fukui University (3῍9῍1 Bunkyo, Fukui 910῍8507, Japan) ylamines.3) However, the PAs of drugs of abuse are not reported yet as far as we know.The kinetic method developed by Cooks et al. is used to determine the PA values of various compounds.
3)῍10)In the kinetic method, the relative abundance of experiments were obtained in the third field-free region of the instrument. All samples (hydrochlorides unless Fig. 1. FAB mass spectrum of the mixture of methylamine (A1) and ethylamine (A2).
Fig. 2. MI spectra (A) and CAD spectra (B) of [A1ῌHClῌA2ῌH]ῌ ions from the mixture of (a) methylamine (A1) and ethylamine (A2), (b) ethylamine (A1) and n-butylamine (A2), (c) dimethylamine (A1) and trimethylamine (A2), and (d) diethylamine (A1) and triethylamine (A2).
The Fragmentation of [M 1ῌHClῌM2ῌH]ῌ (M1, M2῍Amines) ῌ from the mixture of methamphetamine (A1) and reference bases (A2).
Fig. 4. MI spectra (A) and CAD spectra (B) of [A1ῌHClῌA2ῌH]ῌ ions from the mixture of (a) 2-...
