Sampling and profiling caffeine and its metabolites from an eyelid using a watercolor pen based on electrospray ionization/mass spectrometry

摘要

Graphical abstractDisplay OmittedHighlights?A novel and non-invasive sampling method was developed for use in electrospray ionization/mass spectrometry (ESI/MS).?Using a watercolor pen, analytes can be collected either by sweeping the surface of the eyelid of a subject or by simply pipetting a solution of an analyte onto the brush.?The methodology is simple and economical, non-invasive, and is suitable for use in monitoring the levels a variety of metabolites produced by a subject over an extended period of time.AbstractA novel and non-invasive sampling method was developed for use in electrospray ionization/mass spectrometry (ESI/MS). The sampling tool, a watercolor pen (brush) that had been rinsed with