Development of sheath-flow probe electrospray ionization (SF-PESI)

Area of Science:

• Analytical Chemistry
• Mass Spectrometry

Background:

• Probe electrospray ionization (PESI) is a direct analysis technique effective for samples with high salt and detergent content.
• Conventional PESI is limited to analyzing wet samples, hindering its application to dry or solid matrices.
• A need exists for a modified PESI technique capable of analyzing diverse sample types, including dry ones, without prior preparation.

Purpose of the Study:

• To develop and evaluate sheath-flow probe electrospray ionization (SF-PESI) for direct sample analysis.
• To overcome the limitations of conventional PESI for dry samples.
• To demonstrate the applicability of SF-PESI to a wide range of real-world samples.

Main Methods:

• SF-PESI involves inserting a metal needle emitter into a fine plastic capillary.
• Continuous solvent flow through the capillary wets the sample surface at the lowest probe position, extracting analytes.
• Extracted analytes are then electrosprayed from the needle tip at a higher position for analysis.

Main Results:

• SF-PESI successfully enabled direct analysis of various sample types.
• The method demonstrated applicability to diverse matrices including narcotics, tablets, currency, fruits, and potatoes.
• No sample pretreatment was required, simplifying the analytical workflow.

Conclusions:

• SF-PESI is a versatile and effective technique for direct analysis of solid and dry samples.
• The method overcomes the wet-sample limitation of conventional PESI.
• SF-PESI offers a simplified approach for analyzing complex real-world samples in fields like forensics and food safety.