Application of capillary supercritical fluid chromatography–double focusing mass spectrometry under negative ion chemical ionization conditions

✍ Scribed by Eric C. Huang; Bruce J. Jackson; Karin E. Markides; Milton L. Lee

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 628 KB
• Volume: 2
• Category: Article
• ISSN: 1040-7685
• DOI: 10.1002/mcs.1220020209

✦ Synopsis

Abstract

The application of mass spectrometry in the negative ion mode with capillary column supercritical fluid chromatography is described. The supercritical fluid chromatography mobile phase (CO~2~) was used as the primary reagent gas to generate thermalized electrons and reagent anions (such as O^−^ and CO~2~^−^). When trace amounts of CH~4~ or NH~3~ gas were also introduced into the chemical ionization source, the mass spectrometer sensitivity was increased. Detection limits (S/N = 5) for heptachlor were determined to be 20 pg and 200 fg for full scan and selected ion monitoring modes, respectively. Mass spectra of a cyclic peptide, valinomycin, obtained with these mixed reagents (CH~4~ + CO~2~ and NH~3~ + CO~2~) gave the molecular anion at m/z 1110 as the most abundant ion and additional fragment ions that yielded peptide sequence information.