Abstract
High- and ultrahigh-throughput label-free sample analysis is required by many applications, extending from environmental monitoring to drug discovery and industrial biotechnology. HTS methods predominantly are based on a targeted workflow, which can limit their scope. Mass spectrometry readily provides chemical identity and abundance for complex mixtures, and here, we use microdroplet generation microfluidics to supply picoliter aliquots for analysis at rates up to and including 33 Hz. This is demonstrated for small molecules, peptides, and proteins up to 66 kDa on three commercially available mass spectrometers from salty solutions to mimic cellular environments. Designs for chip-based interfaces that permit this coupling are presented, and the merits and challenges of these interfaces are discussed. On an Orbitrap platform droplet infusion rates of 6 Hz are used for analysis of cytochrome c, on a DTIMS Q-TOF similar rates were obtained, and on a TWIMS Q-TOF utilizing IM-MS software rates up to 33 Hz are demonstrated. The potential of this approach is demonstrated with proof of concept experiments on crude mixtures including egg white, unpurified recombinant protein, and a biotransformation supernatant.
Highlights
High- and ultrahigh-throughput label-free sample analysis is required by many applications, extending from environmental monitoring to drug discovery and industrial biotechnology
Coupling of High-throughput screening (HTS) microfluidics to mass spectrometers is commonly achieved through the incorporation of a liquid outlet similar to that of an electrospray (ESI) or nanoelectrospray emitter into a chip, allowing for direct infusion of the analytes into the ion source.[30−32] Droplet microfluidics directly coupled with Mass spectrometry (MS) has been hindered by the need to extract or divert the analyte-containing phase from the separative phase prior to MS infusion.[33−35] Separative phases can contaminate MS instrumentation, and dual-phase fluidics can lead to Taylor cone instability and inadequate electrospray ionization
We have demonstrated the coupling of microdroplet microfluidics with mass spectrometry on three instrument platforms from different MS vendors
Summary
High- and ultrahigh-throughput label-free sample analysis is required by many applications, extending from environmental monitoring to drug discovery and industrial biotechnology. Droplet microfluidic chips have been successfully coupled to a wide range of analytical instrumentation, including fluorescence[20] and optical detection,[21] mass spectrometry,[22,23] Raman spectroscopy,[24] and NMR,[25] with each droplet considered as an individual sample or reaction vessel Combining these techniques with microfluidics supplied analyte at speeds up to 10 000 droplets/s26 and facilitates highthroughput screening in an alternative arrangement to microtiter plate formats. High-throughput microdroplet infusion with MS detection for HTS with a throughput of up to 10 Hz was reported by Steyer et al in 2019; we note that this was implemented in selected ion monitoring mode,[36] with commensurate sensitivity gains, compared with measuring a full mass spectrum
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
