Enhanced analysis of sulfonated azo dyes using liquid chromatography/thermospray mass spectrometry

Abstract

Modifications to a thermospray vaporizer probe and ion source have been made that enhance ion evaporation resulting in increased sample ion current. These modifications include restricting the thermospray vaporizer exit orifice and the addition of a needle-tip repeller electrode to the thermospray ion source. The interaction and effect of probe-tip size, repeller voltage, and flow rate on sulfonated azo dye detection are reported. An increase in signal response for sulfonated azo dyes was observed. An efficient chromatographic separation procedure for sulfonated azo dyes, which is compatible with thermospray mass spectrometric detection, is also presented. Five disulfonated azo dyes were separated and detected by using selected ion monitoring. Mass spectra of disulfonated dyes show a number of molecular ions and adduct ions that provide unequivocal molecular weight information.

Study of the mass spectrometric behaviour of phthalocyanine and azo dyes using electrospray ionisation and matrix‐assisted laser desorption/ionisation

“…Unambiguous identification in these methods relies on mass spectrometry in hyphenated techniques such as HPLC/MS8 and CZE/MS 9. Such MS techniques have generally only been found to be of value in dye characterisation when the dye concentrations are relatively high, e.g., Edmund et al 10 and Ballantine et al 11 using ESI‐MS and McLean et al 12 using Thermospray‐MS.…”

Chemistry of 1,8-Naphthalenesultone: Synthesis of a Water-Soluble Tetrasulfonated C2v Calixnaphthalene

“…That these signals are singlets and that all the other signals in the ambient-temperature 1 H NMR spectrum are sharp is indicative of conformational flexibility. The IR spectrum is also consistent with 6 , but a mass spectrum could only be obtained by electrospray mass spectrometry (ESMS) , in the negative-ion mode, using an aqueous solution of 6 . Suitable crystals for single-crystal X-ray analysis or elemental analysis have not yet been obtained.…”

Enhanced analysis of poly(ethylene glycols) and peptides using thermospray mass spectrometry

“…This indicates that the repeller potential only affects ion mobility and not the ionization process, which can be different for positive and negative ions. Experiments for other compounds also indicate that increased ion diffusion is a predominant effect (23). In addition, preliminary experiments indicate that changing the distance of the repeller tip from the ion exit aperture changes the absolute value of the optimum repeller potential, but not the value of the maximum ion current (19).…”

“…This distance was optimal for signal response on our instrument (19). The vaporizer probe was modified as described elsewhere (23) to include a tip with a fused silica capillary tube (100 fim i.d. )…”