Nanoelectrode Atmospheric Pressure Chemical Ionization Mass Spectrometry

• Published in: Journal of the American Society for Mass Spectrometry Vol. 35; no. 10; pp. 2288 - 2296
• Main Authors: Auvil, Nicole C., Bier, Mark E.
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02-10-2024
• Subjects: tungsten needle; corona needle; gas-phase analysis; mass spectrometry; corona discharge; APCI; atmospheric ionization
• ISSN: 1044-0305; 1879-1123; 1879-1123
• DOI: 10.1021/jasms.4c00117

A small ionization needle with an ultrasharp, ultrafine tip is introduced. It is lab-fabricated from tungsten wire and serves as a corona discharge emitter in nanoelectrode atmospheric pressure chemical ionization mass spectrometry (nAPCI-MS). Tip radii ranged from 8 to 44 nm, up to 44× smaller than the sharpest previously reported corona needle. Because of this, nAPCI was able to operate at +1.0 kV with no auxiliary counter electrode. Alternatively, at +1.2 kV, nAPCI could be enclosed in a small plastic assembly for headspace analysis with a sampling tube attachment as long as 15 m. No added heat or gas flow was necessary. The efficacy of nAPCI-MS was demonstrated through needle durability studies and direct analysis of vapors from real-world samples. Provisional identifications include ibuprofen from a pharmaceutical tablet, albuterol aerosol sprayed from a medical inhaler, cocaine from paper currency, caffeine from a fingertip, and bisphenol E from a paper receipt.