ION CHROMATOGRAPHY MASS-SPECTROMETRY FOR THE DETERMINATION OF ORGANIC AMMONIUM AND SULFATE COMPOUNDS

The ion spray liquid chromatography/mass spectrometry (LC/MS) Interface Is coupled via a postsuppressor split with an ion chromatography (IC) system. The micromembrane suppressor selectively removes over 99.9 % of the ion-pair agents required for ion chromatography from the eluent. The resulting solution consists of analyte, organic modifier, and water, which is compatible with Ion evaporation mass spectrometry. A flow rate of 0.8 or 1.0 mL/min from the column was split after suppression such that approximately 10–20 μL/min was directed to the ion spray LC/MS interface, which was coupled to an atmospheric pressure ionization (API) mass spectrometer. This system provided a convenient way to effect lsocratic and gradient separations of organic ions under chromatographic conditions incompatible with most forms of mass spectrometric ionization. This work describes the separation and positive ion detection of quaternary ammonium drugs and tetraalkylammonlum compounds of industrial importance using both single and tandem mass spectrometric detection (e.g., IC/MS and IC/MS/MS). The former easily provided the molecular weights of these compounds while the latter gave some structural information. The limit of detection (LOD) of 40 pg Injected on-column for tetrapropylammonlum cation Is a factor of 10 better than that obtained with the conventional IC conductivity detector. The separation, detection, and Identification of some alkyl sulfates and sulfonates are also shown with negative Ion detection. Again, IC/MS readily produced the molecular weights of these compounds while IC/MS/MS provided some structural information. © 1990, American Chemical Society. All rights reserved.