Atmospheric Pressure Photoionization (APPI) is an ionization technique available on all Agilent LCMS product models including single quad, triple quad and QTOF instruments. The LC eluent is vaporized using a heater at atmospheric pressure. The resulting gas is made to pass through a beam of photons generated by a discharge lamp (UV lamp) which ionizes the gas molecules.
The Thermo Scientific Ion Max ion source, with combination APCI / APPI, allows for effective ionization of non-polar compounds. This unique ion source provides greater flexibility and the capability to analyze a larger range of compounds without changing hardware.
The XEVO™ APCI / APPI probe introduces samples into the ion source, incorporating a Syagen Technologies 10.6 ev krypton discharge UV lamp. The lamp emits photons that excite analyte molecules and subsequently produce ions through electron ejection. In this process, sample molecules are preferentially ionized when the photon energy exceeds their ionization potential, but is lower than the ionization potential of the surrounding vaporized LC eluent.