Gas chromatography combined with flame-induced atmospheric pressure chemical ionization mass spectrometry for the analysis of fatty acid methyl esters and saturated hydrocarbons

• Published in: Analytica chimica acta Vol. 1200; p. 339611
• Main Authors: Cheng, Sy-Chyi, Lin, Hsing-Jung, Lee, Chi-Yang, Huang, Min-Zong, Shiea, Jentaie
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01-04-2022
• Subjects: Atmospheric Pressure; Esters - analysis; Fatty acid methyl ester; Fatty Acids - analysis; Flame-induced atmospheric pressure chemical ionization; Gas Chromatography-Mass Spectrometry - methods; GC-MS interface; Hydrocarbons; Mass Spectrometry; Micro-flame; Micro-flame; Flame-induced atmospheric pressure chemical ionization; Fatty acid methyl ester; GC-MS interface
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2022.339611

A simple flame-induced atmospheric pressure chemical ionization (FAPCI) source was developed to couple a gas chromatograph (GC) with a mass spectrometer (MS). The interface consisted of a heated transfer line and a high voltage-free ambient FAPCI source. Nitrogen gas flowing through the heated transfer line was utilized to deliver the analytes eluted from a GC column to the ionization region. A micro oxyacetylene flame was positioned under the exit of heated transfer line, which generated primary charged species in the ionization region. Since the temperature at the ionization region was below 200 °C, the analytes were not thermally decomposed. Protonated analytes were formed by reacting the analytes with flame-induced charged species through ion-molecule reactions (IMRs). The simple GC-FAPCI/MS was used to characterize a series of fatty acid methyl esters (FAMEs) and long-chain normal alkanes, which showed protonated FAME and oxidized n-alkane ions on the mass spectra. The limits of detection (LODs) for C15:0 to C25:0 FAMEs were 1–2.5 pg. A calibration curve ranging from 2.5 to 500 pg, with a R2 value of 0.9821, was obtained.
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•A simple and efficient FAPCI source was developed to interface GC and MS.•Protonated FAMEs and oxidation products of n-alkanes were detected on the MS spectra.•The LOD of FAMEs detected by GC-FAPCI/MS was in picogram level.