title: On-chip spyhole mass spectrometry for droplet-based microfluidics.
abstract: For efficient coupling of droplet-based microfluidics with mass spectrometry (MS), a spyhole drilled on the top of a microchip is used to sample the passing droplets by electrostatic-spray ionization (ESTASI) MS. The technique involves placing an electrode below the chip under the spyhole and applying high-voltage pulses. Electrospray occurs directly from the spyhole, and the droplet content is analyzed by MS without a dilution or oil removal step. To demonstrate the versatility of this technique, we have successfully monitored a droplet-based tryptic digestion, as well as a biphasic reaction between β-lactoglobulin in water and α-tocopheryl acetate in 1,2-dichloroethane, where the protein extracts the antioxidant from the oil phase and becomes reduced.
authors.affiliation: Laboratoire d'Electrochimie Physique et Analytique, Ecole Polytechnique Fédérale de Lausanne, Station 6, 1015 Lausanne (Switzerland) http://lepa.epfl.ch.
authors.forename: Natalia
authors.initials: N
authors.lastname: Gasilova
authors.forename: Qiuliyang
authors.initials: Q
authors.lastname: Yu
authors.forename: Liang
authors.initials: L
authors.lastname: Qiao
authors.forename: Hubert H
authors.initials: HH
authors.lastname: Girault
keywords: biphasic reactions; electrostatic spray; mass spectrometry; microdroplets; microreactors