Field ionization mass spectrometric sensitivities of one-ring aromatic hydrocarbons

Abstract

Field ionization mass spectrometric sensitivities of xylene and nine monosubstituted one-ring aromatic hydrocarbons have been investigated toward the establishment of an alternative method for quantitative hydrocarbon characterization and [open quotes]type analysis[close quotes]. The molar sensitivity, relative to toluene, is found to increase nonlinearly as the chain length of the alkyl substitution on the ring is increased. This increase of sensitivity is consistently observed under the different ion source conditions investigated. The source temperature is found to affect the sensitivity significantly. The sensitivity of compounds with longer chain length was found to increase more, relative to those with shorter chain length, when the temperature is lowered. The standard deviations of the data also increased with the decrease of temperature. The most reproducible results were obtained at 250[degrees]C, the highest temperature studied. These effects may be attributable to adsorption phenomenon on the emitter as pointed out earlier by others. There was no discernible change in the measured sensitivities with changing solute concentration when hexane and pentane were used as solvents. 35 refs., 3 figs., 3 tabs.