Soft X-ray Atmospheric Pressure Photoionization in Liquid Chromatography-Mass Spectrometry.

ABSTRACT: Soft X-ray atmospheric pressure photoionization (soft X-ray APPI) as an ionization method in liquid chromatography-mass spectrometry (LC-MS) is presented. The ionization mechanism was examined with selected test compounds in the negative ion mode, using soft X-ray APPI source emitting 4.9 keV photons. Test compounds with an acidic group were ionized by a proton transfer reaction, producing deprotonated molecules ([M - H]^-), whereas compounds having positive electron affinity were ionized by a charge exchange reaction, producing negative molecular ions (M^-•). Soft X-ray APPI does not require a dopant to achieve high ionization efficiency, which is an advantage compared with vacuum ultraviolet APPI with 10 eV photons, in which a dopant is needed to improve ionization ef

SUBMITTER: Hieta JP 

PROVIDER: S-EPMC8382217 | biostudies-literature | 2021 Jul

REPOSITORIES: biostudies-literature