Composition of water cluster ions under ionization conditions at atmospheric pressure

Atmospheric Pressure Photoionization: An Ionization Method for Liquid Chromatography−Mass Spectrometry

“…As part of the introduction to the use of photoionization with LC−MS, any prior reports of APPI combined with mass spectrometry must also be considered. There has never been a widely applied or studied mass spectrometry technique that utilized PI at atmospheric pressure, and, while there have been numerous examples of APPI coupled with ion mobility spectrometry (PI-IMS; for examples, see refs −10), we have found only two reports of true mass analysis of photoions created at atmospheric pressure. , In these first APPI-MS experiments that demonstrated the feasibility of the combination, direct analysis was performed of vaporized samples that were transported to the ionization region by a flow of helium carrier gas. A hydrogen discharge lamp ( h ν = 10.2 eV) was utilized to create ions for a quadrupole mass analyzer.…”