Single Photon Ionization/Photoelectron Ionization-Membrane Introduction Mass Spectrometry for On-line Analysis Ethers Gasoline Additive in Water

A magnetic field enhanced photoelectron ionization (MEPEI) source combined with single photon ionization (SPI) for membrane inlet time-of-flight mass spectrometry was used for on-line detection of ether gasoline additive. Methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), methyl tert-amyl ether (TAME) and isopropyl ether (DIPE) were selected as the typical pollutants. A membrane inlet was used to transfer the analytes from liquid into gas phase in an on-line manner by pervaporization without sample pretreatment. Less sample fragments were in SPI, and molecular ions could be used to quick preliminarily qualitative analysis; high energy electrons and fragmentations produced by MEPEI can be used to accurate qualitative isomers and overcame the problem of resolution of overlapping peaks in complex matrix when using direct injection. Under the optimal conditions such as membrane temperature 60 degrees C, membrane thicknesses 50 mu m and membrane areas 160 cm(2), the single sample analysis time was less than 100 s, and the limits of detection for MTBE, ETBE, TAME and DIPE were 5.5, 4.8, 3.3 and 4.3 mu g/L, respectively. The instrument has been successfully applied to rapid analysis of MTBE in simulated water by gasoline.