Mass-spectrometric studies of kinetic characteristics of codeine molecule thermodesorption by non-stationary surface ionization method.

The adsorption and surface ionization of codeine molecules С 18 H 21 O 3 N ( m/z 299) on the surface of oxidized tungsten have been studied by a non-stationary method of voltage modulation under the same experimental conditions with a high-vacuum mass-spectrometric setup using a "black chamber" all walls of which are cooled with liquid nitrogen. For the codeine molecule dissociation with the ( C - C 1 ) β bond breaking and formation of ionizable radicals, the rate constants K + and K 0 , the activation energy Е + and Е 0 of thermodesorption, and the pre-exponential factors in the continuity equation for the radicals C 9 H 7 N + CH 3 ( m/z 144) have been defined by surface ionization on the surface of oxidized tungsten W x O y . The results of determining the surface ionization coefficient and estimates of the ionization potentials of these radicals have been presented.