Examination of the effect of air atmosphere on heterogeneous reactions under surface ionization of psychotropic drug molecules

Abstract

The results of mass spectrometric studies of surface ionization of molecules of psychotropic drugs such as chlorpromazine, amitriptyline and medazepam in an air atmosphere have been presented. The channels of heterogeneous reactions occurring during the molecule adsorption on the hot surface of the thermoemitter from refractory metal oxides have been revealed, as well as the influence of air atmosphere on these reactions. A strong influence of the air atmosphere on the heterogeneous association reactions with the emission of [M + H]+ ions has been found. This ion line is the main in the mass spectra of all the substances under study instead of the characteristic main line in the surface ionization mass spectra obtained in vacuum. The effect of air on the reactions of dehydrogenation and dissociation of adsorbed molecules of organic compounds has been insignificant. In the surface ionization mass spectra of all the substances studied under atmospheric conditions the adduct cluster ions М⋅[М−R]+, М⋅[М−Н]+ and М⋅[М+Н]+ (where М is the molecule, R is the radical, H is the hydrogen atom) up to М⋅[М+Н]+⋅HCl. They are probably formed by adhesion of analyte molecules to the primary ions [М−R]+, [М−Н]+ and [М+Н]+. A comparative analysis has been also performed with the data obtained by chromato-mass spectrometry with electron ionization, as well as with the surface ionization data for these preparations obtained under high vacuum.