Development of high-pressure probe electrospray ionization for aqueous solution.

Area of Science:

• Analytical Chemistry
• Mass Spectrometry

Background:

• Probe electrospray ionization (PESI) is a direct analysis method suitable for various samples, but suffers from poor ion signal stability and reproducibility in aqueous solutions due to corona discharge.
• Ambient conditions like humidity and contaminants in open-environment PESI further degrade performance.

Purpose of the Study:

• To develop a modified PESI technique that improves ion signal stability and reproducibility for aqueous samples.
• To address the limitations of corona discharge and environmental influences in conventional PESI.

Main Methods:

• A modified PESI approach, termed high-pressure PESI (HP-PESI), was developed where electrospray and droplet desolvation occur within a chamber pressurized with dry air (>1 atm).
• A comparative study was conducted between atmospheric-pressure PESI and HP-PESI to evaluate performance improvements.

Main Results:

• HP-PESI enables stable electrospray initiation, even for high surface tension liquids like pure water, by enhancing gas dielectric strength and preventing corona discharge.
• HP-PESI demonstrated significantly improved sensitivity and signal stability for detecting analytes in aqueous solutions compared to atmospheric-pressure PESI.

Conclusions:

• HP-PESI offers superior sensitivity and signal stability over conventional PESI.
• Key advantages of HP-PESI include the absence of gaseous breakdown, enhanced desolvation, and a higher ion sampling rate for mass spectrometry.