A GC-LIF System for Specific Detection of Multifunctional RONO2

Measurements of the isomeric specific yields of organic nitrates from the addition of NO3 to alkenes (e.g isoprene, limonene) remain a challenge, impeding development of detailed mechanistic understanding of VOC oxidation. A new detector based on thermal dissociation laser induced fluorescence (TD-LIF) technique has been optimized for use with gas chromatography (GC) hence providing both high specificity and high sensitivity detection toward organic nitrates. This instrument is especially attractive when analyzing samples of complex mixtures, commonly encountered in environmental samples and chamber experiments. In addition, no sample pre-treatment and better baseline stability when compared to ECD detection ensure simpler quantification as such detector has the advantage of uniform sensitivity towards organic nitrate functional groups, making sampling the main limitation to accurate quantification. Calibration of the system is achieved with an alternative flow path to the LIF detection cell directly feeding certified gas standard with known concentration of NO2 along with a range of multifunctional organic nitrates that were synthesized in our laboratory. Performance of the system will be illustrated with application to reactions of biogenic VOC with NO3.