DIRECT DETERMINATION OF ORGANIC-COMPOUNDS IN WATER AT PARTS-PER-QUADRILLION LEVELS BY MEMBRANE INTRODUCTION MASS-SPECTROMETRY

Parts-per-quadrillion level detection of toluene and trans-1,2-dichloroethene in water has been achieved on-line, without preconcentration, by employing selective ionization in conjunction with membrane introduction ion trap mass spectrometry. The stored wave form inverse Fourier transform technique is used to create broad-band wave forms, notched at the resonance frequencies of analyte ions of interest. A series of such pulses is applied during ionization to eject unwanted ions and store only analyte ions. This capability is used over long ionization times to obtain extraordinarily low detection limits for aqueous solutions of volatile organic compounds, introduced into the ion trap using a silicone membrane located within in a commercially available capillary membrane inlet system.