Abstract: A method and apparatus for probing the chemistry of a single droplet are provided. The technique uses a variation of the field-induced droplet ionization (FIDI) method, in which isolated droplets undergo heterogeneous reactions between solution phase analytes and gas-phase species. Following a specified reaction time, the application of a high electric field induces FIDI in the droplet, generating fine jets of highly charged progeny droplets that can then be characterized. Sampling over a range of delay times following exposure of the droplet to gas phase reactants, the spectra yield the temporal variation of reactant and product concentrations. Following the initial mass spectrometry studies, we developed an experiment to explore the parameter space associated with FIDI in an attempt to better understand and control the technique.