| Abstract: | The O?˙ chemical ionization mass spectrri of the C8H10 alkylbenzenes, o-, m-. andp -xylene and ethylbenzene, show formation of [M ? H + O]?, [M ? H]?, [M ? H2]?˙ and, for the xylenes, [M ? CH3 + O]? as primary reaction products; the relative importance of these products depends on the isomer. However, [OH]? is a primary product from reaction of O?˙ with both the C8H10 isomers and hydrogen-containing impurities; [OH]? reacts further with the alkylbenzenes to produce [M ? H]? with the result that the chemical ionization mass spectra depend on experimental conditions such as sample size and the presence of impurities. The collision-induced charge inversion mass spectra of the [M ? H + O]? and [M ? H]? products allow only distinction of ethylbenzene from the xylenes. However, the collision-induced charge inversion mass spectra of the [M ? H2]?˙ ions show differences which allow identification of each isomer. |
