Thin-layer chromatography/electrospray ionization triple-quadrupole linear ion trap mass spectrometry system: Analysis of rhodamine dyes separated on reversed-phase C₈ plates

The direct analysis of separated rhodamine dyes on reversed-phase C ₈ thin-layer chromatography plates using a surface sampling/electrospray emitter probe coupled with a triple-quadrupole linear ion trap mass spectrometer is presented. This report represents continuing work to advance the performance metrics and utility of this basic surface sampling electrospray mass spectrometry system for the analysis of thin-layer chromatography plates. Experimental results examining the role of sampling probe spray end configuration on liquid aspiration rate and gas-phase ion signal generated are discussed. The detection figures-of-merit afforded by full-scan, automated product ion and selected reaction monitoring modes of operation were examined. The effect of different eluting solvents on mass spectrum signal levels with the reversed-phase C8 plate was investigated. The combined effect of eluting solvent flow-rate and development lane surface scan rate on preservation of chromatographic resolution was also studied. Analysis of chromatographically separated red pen ink extracts from eight different pens using selected reaction monitoring demonstrated the potential of this surface sampling electrospray mass spectrometry system for targeted compound analysis with real samples.