High-resolution analysis of a 144-membered pyrazole library from combinatorial solid phase synthesis by using electrospray ionisation Fourier transform ion cyclotron resonance mass spectrometry

A compound library consisting of 144 pyrazole carboxylic acids and six subl ibraries consisting of 24 components was analysed using electrospray ionisa tion Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR -MS). The library was synthesised by the split-mix method and investigated by direct infusion analysis by which 134 compounds were detected. FTICR-MS is predestined for the direct characterisation of complex compound librarie s because of its outstanding mass resolution and mass accuracy. However, di scrimination within the electrospray ionisation process sometimes leads to signal suppression and thus to misinterpretation of the synthetic results. Using micro-HPLC/MS we were able to assign all 144 compounds including all pairs of isobaric pyrazoles. We also show that, due to partial separation, FTICR-MS is indispensable for proper detection of co-eluting compounds. Cop yright (C) 2001 John Wiley & Sons, Ltd.