Nanoelectrode Atmospheric Pressure Chemical Ionization Mass Spectrometry

Area of Science:

• Analytical Chemistry
• Mass Spectrometry
• Materials Science

Background:

• Traditional corona needles limit atmospheric pressure chemical ionization mass spectrometry (APCI-MS) applications.
• Existing methods often require high voltages, auxiliary electrodes, or specific environmental conditions.

Purpose of the Study:

• To introduce a novel, ultrasharp tungsten ionization needle for nanoelectrode APCI-MS (nAPCI-MS).
• To demonstrate the capability of nAPCI-MS using this new needle for simplified and versatile vapor analysis.

Main Methods:

• Lab-fabrication of tungsten wire ionization needles with tip radii from 8 to 44 nm.
• Operation of nAPCI-MS without auxiliary electrodes or with a compact assembly for headspace analysis.
• Durability testing and direct vapor analysis of various real-world samples.

Main Results:

• The ultrasharp needle enabled nAPCI-MS operation at +1.0 kV without a counter electrode.
• nAPCI-MS operated effectively at +1.2 kV within a small assembly, allowing for long sampling tubes (15 m).
• Successful identification of compounds like ibuprofen, albuterol, cocaine, caffeine, and bisphenol E from diverse sources.

Conclusions:

• The developed ultrasharp ionization needle significantly enhances nAPCI-MS performance and portability.
• This technology facilitates direct, sensitive analysis of vapors from pharmaceuticals, aerosols, and everyday materials.
• The nAPCI-MS system offers a simplified, low-voltage alternative for on-site chemical analysis.