Chemical Microreactors in Combination with Mass Spectrometry

The application of the “Lab-on-a-Chip” concept to synthetic chemistry [1, 2] is still at its infancy. In this work a borofloat microchip (Fig. 1) was designed and fabricated by means of the powderblasting technique and used as chemical microreactor in which different solution-phase syntheses have been performed successfully. The stream flowing from the outlet of the chip has been transferred directly onto a gold-coated sample plate. The chemical reaction products were analysed using matrix assisted laser desorption ionization [MALDI] - time-of-flight [TOF] mass spectrometry [3]. MALDI-TOF mass spectrometry in combination with post source decay [PSD] experiments shows to be an excellent method in obtaining molecular weights and structural information. The Schiff base reaction, in which primary amines react with aldehydes to give imines, was chosen as a primary study, because the Schiff base reaction is straightforward and products are obtained in high yields. Lab-scale experiments are carried out under acidic conditions (pH = 3–4), however, pH control is not necessary under the “Labon-a-Chip” conditions. Open image in new window Figure 1 Schematic representation of the chip used in this work and of the MALDI sample plate on which the stream flowing from the chip is analysed.