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On‐Chip Spyhole Mass Spectrometry for Droplet‐Based Microfluidics
Author(s) -
Gasilova Natalia,
Yu Qiuliyang,
Qiao Liang,
Girault Hubert H.
Publication year - 2014
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201310795
Subject(s) - microfluidics , mass spectrometry , chemistry , electrospray ionization , electrospray , dilution , chromatography , analytical chemistry (journal) , electrohydrodynamics , electrode , nanotechnology , materials science , physics , thermodynamics
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.