A MALDI-chip integrated system with a monitoring window

The integration of a monitoring port along the microfluidic path of a MALDI-chip integrated device is described. Optimization of the microreactor design allows longer reaction and measuring times. The Schiff base reaction between 4-tertbutylaniline ( 1) and 4-tert-butylbenzaldehyde ( 2) in ethanol was carried out on-chip in the MALDI ionization chamber and the formed imine 3 was detected in real time, demonstrating the feasibility of the monitoring window'' approach. This preliminary result opens the way to on-chip kinetic studies by MALDI-MS, by opening multiple monitoring windows along the microchannel.