Studies in mass spectrometry. Part XXXII. The kinetic approach to mass spectrometry

Abstract

Experimental results have shown that, for a number of compounds investigated, the relative ion abundances at the collector are a function of the time, t₂, taken to reach the collector from the source. Experimental support for the ‘instrument constant,’ introduced by Bursey and McLafferty, is given. Extrapolation to the source value of [A⁺]/[M⁺](from the measured collector value of [A⁺]/[M⁺] for the reaction M⁺→ A⁺) is impossible with any accuracy where accelerating voltages higher than 8 kV cannot be used. However, in the substituent effects investigated, changes in [A⁺]/[M⁺] between source and collector are probably sufficiently similar from compound to compound not to necessitate modification of the steady-state theory on that account alone. It is emphasised that this result is related to important contributions to recorded M⁺ intensities from ions with insufficient energies to decompose, and it then follows that [A⁺]/[M⁺] is a function of the rates of competing unimolecular decompositions.