A Novel APPI-MS Setup for In Situ Degradation Product Studies of Atmospherically Relevant Compounds: Capillary Atmospheric Pressure Photo Ionization (cAPPI)

Abstract

We report on the development of a novel atmospheric pressure photoionization setup and its applicability for in situ degradation product studies of atmospherically relevant compounds. A custom miniature spark discharge lamp was embedded into an ion transfer capillary, which separates the atmospheric pressure from the low pressure region in the first differential pumping stage of a conventional atmospheric pressure ionization mass spectrometer. The lamp operates with a continuous argon flow and produces intense light emissions in the VUV. The custom lamp is operated windowless and efficiently illuminates the sample flow through the transfer capillary on an area smaller than 1 mm 2 . Limits of detection in the lower ppbV range, a temporal resolution of milliseconds in the positive as well as the quasi simultaneously operating negative ion mode, and a significant reduction of ion transformation processes render this system applicable to real time studies of rapidly changing chemical systems. The method termed capillary atmospheric pressure photo ionization (cAPPI) is characterized with respect to the lamp emission properties as a function of the operating conditions, temporal response, and its applicability for in situ degradation product studies of atmospherically relevant compounds, respectively.

Gas Flow Dynamics in Inlet Capillaries: Evidence for non Laminar Conditions

“…A laminar flow ion source (LFIS), introduced by Barnes et al [4,23,25], or a custom ionization chamber were mounted upstream of the inlet capillary. The volume flow through the inlet capillary was measured by a drum type gas flow meter (TG05, Ritter Apparatebau GmbH and Co. KG, Bochum, Germany), which was attached to the entrance of the capillary.…”

Gas chromatography coupled to atmospheric pressure ionization mass spectrometry (GC-API-MS): Review

“…Capillary photoionization (CPI) [55] and capillary APPI (cAPPI) [80] are variants of APPI. In both ion sources the APPI process occurs within the confined volume of a capillary, but differs in the types of VUV source and whether or not they employ a VUV window.…”

Ionization of EPA Contaminants in Direct and Dopant-Assisted Atmospheric Pressure Photoionization and Atmospheric Pressure Laser Ionization

“…As an LC-MS interface, APPI has been applied widely in e.g., pharmaceutical, biological, and environmental analysis [3,4]. Although APPI was originally developed for LC-MS, there is also an increasing number of reports using it as an interface for GC-MS [5][6][7][8][9][10][11][12]. A major advantage of GC compared with LC is its much higher peak capacity, which allows the separation of a much higher number of compounds in one chromatographic run.…”