Remote sampling mass spectrometry for dry samples: Sheath‐flow probe electrospray ionization (PESI) using a gel‐loading tip inserted with an acupuncture needle

Abstract

Because of its simplicity and versatility, sheath-flow PESI is a promising technique for on-site and nondestructive profile analysis of dry samples with bulky and complicated shapes, with a spatial resolution of ~0.3 mm.

Sheath-flow probe electrospray ionization (sfPESI) mass spectrometry for the rapid forensic analysis of human body fluids

“…The amount of sample required in sfPESI has been estimated to be in the order of picograms, thus the technique can be used with minute sample amounts. 28 Most importantly, the sequential ionisation observed with sfPESI enables the temporal separation of ions, offering the possibility of limiting ion suppression and visualising more analytes in such a way that has not been observed in other electrospray techniques such as LESA. The principles of this sequential ionisation have been described in greater detail in a recent paper by Usmanov et al 28…”

“…27 However as PESI is only applicable to liquid samples, sheath-ow PESI (sfPESI) was later developed to enable the analysis of non-liquid samples. 28,29 Sheath-ow PESI is a modication of the PESI technique in which the needle is contained within a solvent-lled gel-loading tip with a slight protrusion (0.1 mm) of the needle from the base. When the probe touches the sample surface, the convex liquid at the base of the probe wets the sample and enables analyte extraction from the surface.…”

“…The mechanism of sfPESI has been described in greater detail elsewhere. 28 Here we present a sheath-ow PESI mass spectrometry technique capable of tackling many of the current downfalls of existing forensic body uid identication techniques. This paper demonstrates the applicability of the method to both fresh and dried blood, saliva and urine, enabling the rapid analysis of complex biological samples, even aer storage for up to 30 days.…”

Direct Liquid Extraction and Ionization Techniques for Understanding Multimolecular Environments in Biological Systems (Secondary Publication)

“…of PESI 136) . A metal needle is inserted into a gel loading tip containing solvent so that the needle tip protrudes slightly.…”

“…Sheath flow PESI (SF-PESI) is a derivative technology of PESI. 136 ) A metal needle is inserted into a gel loading tip containing solvent so that the needle tip protrudes slightly. Sample extraction is performed by touching the needle to the sample, and ESI is performed by applying a high voltage to the needle.…”