Probe electrospray ionization

Probe electrospray ionization (PESI) is a technique used in mass spectrometry for the ionization of samples, particularly in the analysis of biomolecules, drugs, and other complex mixtures. It is a variant of electrospray ionization (ESI), which is a widely used ionization method. In PESI, a probe is used to directly sample the analyte from a solid or liquid surface.