Supersonic jet/multiphoton ionization/time-of-flight mass spectrometry for dioxin analysis: Effect of solvent in solution inlet/laser vaporization technique Original Research Article

The effect of solvent on the solution inlet/laser vaporization technique for multiphoton ionization/time-of-flight mass spectrometry (MPI/TOF-MS) was examined. In this technique, a sample of dibenzofuran, dissolved in an organic solvent, is introduced underneath the nozzle for jet expansion through a narrow capillary, at the end of which a glass frit is formed to vaporize the solvent and to deposit the analyte for laser vaporization. The ion signal, consisting of irregular peaks, is increased by the introduction of a laser pulse for vaporization, when methanol is used as a solvent. This can be attributed to local boiling of the solution at the surface of the frit due to the volatile nature of methanol. When glycerin was added to the methanol, the irregular peaks were substantially decreased. However, an increase in signal intensity was not observed by laser vaporization when the glycerin content was increased to 50%. In the case of n-nonane, which is currently used as a solvent for dissolving dioxin standards, no irregular peaks were observed and the signal intensity was increased by laser vaporization.