Continuous on-line determination of methyl tert-butyl ether in water samples using ion mobility spectrometry

A rapid analytical procedure for the on-line determination of methyl tert-butyl ether (MTBE) in water samples was developed. A new membrane extraction unit was used to extract the MTBE from water samples. The concentration of MTBE was determined using ion mobility spectrometry with 63Ni ionization and corona discharge ionization without chromatographic separation. Both ionization methods permit the sensitive determination of MTBE. A detection limit of 100 μg/L was established for the on-line procedure. Neither the inorganic compounds, humic substances nor gasoline were found to exert a significant influence on the peak intensity of the MTBE. The screening procedure can be used for concentrations of monoaromatic compounds (benzene, toluene, xylene) up to 600 μg/L. No sample preparation is required and the analysis results are available within 5 min. In order to determine concentrations between 10 μg/L and 100 μg/L, a discontinuous procedure was developed on the basis of the same experimental set-up.