Hot-stage microscopy - Direct Analysis in Real-time mass spectrometry (HDM) as a novel tool for monitoring thermally-driven reactions on a small scale

There is a requirement for reliable real-time analytical tools for reaction monitoring to optimise chemical syntheses. We have developed a new technique which combines thermal analysis, digital microscopy and chemical identification using ambient ionisation mass spectrometry. We term this hot-stage microscopy-Direct Analysis in Real-Time mass spectrometry (HDM). The technique provides optical data as a function of temperature coupled with chemical characterisation of evolved species, including reactants, intermediates and products throughout the course of a reaction. In addition, only a few milligrams of sample are required with analyte detection down to the nanogram range. We demonstrate the benefits of HDM using a series of solvent-free reactions. Our results confirm the suitability of the technique as the reactions studied follow the same pathways as published previously. The accurate temperature control achieved with HDM could also be used to assess the optimum temperature at which thermally-driven reactions can proceed efficiently.