||Enhanced Sensitivity in Liquid Chromatography/Thermospray Mass Spectrometry of Dyes Using a Wire Repeller.
Yinon, J. ;
Jones, T. L. ;
Betowski, L. D. ;
||Weizmann Inst. of Science, Rehovoth (Israel).;Environmental Monitoring Systems Lab., Las Vegas, NV.
Azo dyes ;
Mass spectroscopy ;
Ion sources ;
Liquid column chromatography
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The need for more sensitive methods of detection for the analysis of dyes has led to the investigation of the use of a repeller in the thermospray ionization source of a liquid chromatography/mass spectrometry instrument. The repeller is actually a wire situated opposite the extraction cone of the ion source and is operated at a voltage of 200-250 V. An increased sensitivity of about two orders of magnitude is reported for Disperse Blue 79, a widely used azo dye. An increase in the relative intensity of the molecular ion versus the fragment ions is also observed. It is believed that the narrow electric field produced between the wire repeller and extraction cone accelerates the ions towards the hole of the cone and thus increases the number of ions entering the analyzer.