Focusing Plasma Desorption/Ionization Mass Spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Plasma Physics

Background:

• Direct analysis of samples using plasma ionization is crucial for mass spectrometry.
• Existing plasma sources often require specialized equipment or have limitations in sensitivity and compatibility.

Purpose of the Study:

• To introduce and characterize a novel plasma-based ionization source, focusing plasma desorption/ionization (FPDI).
• To evaluate the performance of FPDI in terms of sensitivity, compatibility, and applicability for various analytical tasks.

Main Methods:

• Development of a focusing plasma desorption/ionization (FPDI) source using a high DC voltage between a metal wire and a conducting paper substrate.
• Optimization of parameters including substrate grounding, cone geometry, electrode distances, voltage, and helium flow rate.
• Coupling FPDI with a mass spectrometer for sample analysis.

Main Results:

• FPDI generates a visible plasma beam for direct sample ionization.
• Signal intensity is influenced by several experimental parameters, with a plausible generation mechanism proposed.
• FPDI demonstrates higher sensitivity and better compatibility with commercial mass spectrometers compared to existing plasma sources.
• Successful application in discriminating gasoline brands and determining solid tablets and pesticides with low detection limits (2.2–30.7 ng mL⁻¹).

Conclusions:

• FPDI is a sensitive and versatile plasma ionization source for mass spectrometry.
• The developed source is compatible with standard mass spectrometers, requiring no additional power supplies.
• FPDI shows significant potential for rapid and sensitive analysis of diverse analytes.