The Gap Sampler: A Versatile Microfluidic Autosampler for Electrospray Ionization Mass Spectrometry

Microfluidic autosamplers for electrospray ionization mass spectrometry (ESI-MS) are of major importance when using ESI-MS as a high-throughput and low sample consumption analytical method. In this article, microfluidic ESI-MS autosampler designs are overviewed and a group-owned prototype is discussed. The socalled gap sampler is a pin-based sampler for miniaturized flow injection (FI) analysis. To date, it has been used in various applications. Following proof of concept applications with FI of small molecules, pin modifications were implemented for unspecific and specific extraction for the analysis of complex samples. Most recently, further optimization allowed the study of non-covalent protein-ligand interactions for bioaffinity screenings, which constitutes a major milestone in the development of this novel high-throughput autosampler.