Fig. 10. Mass spectra for the Hantzsch synthesis conducted in the bulk (a) and in ESSI droplets with no transfer tube (b), with a 55 cm tube before cleaning (c) and after cleaning with acetone wash (d). Label color (same as in eqn (8)): red = reagents, purple = reaction intermediates, green = product, grey = peaks from impurities. In parentheses the labels for each reagent, intermediate and product molecule from eqn (8); all ions are [M + H]⁺.