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Eisenhauer, Jessica Mendes

Chemistry

2013

MS

Investigation of tropospheric chemistry has advanced in recent years with the wide adoption of instrumentation that allows collection and preconcentration of whole air samples coupled with improved GC-MS interfaces. These developments have led to the ability to analyze trace components in ambient air in the low-ppbv range. Herein we present the University of Vermont Environmental Chamber (UVMEC) which allows for the generation and measurement of low-level oxidants inside the batch reaction chamber. Measurement capabilities include on-line near infrared -- laser desorption ionization - aerosol mass spectrometry, scanning mobility particle sizing, thermal desorption -gas chromatography -mass spectrometry and continuous temperature, ozone and NOx concentration monitoring.
We have established and validated a new quantitative method for the 1-step determination of terpenoids and selected oxidation products such as aldehydes, ketones and carboxylic acids without derivatization. Proof of principle is presented for both the UVMEC's abilities for oxidant generation and measurement as well as the new TD-GC-MS methods. In this work, isoprene, [alpha]-pinene, limonene, aromadendrene and trans-caryophyllene are determined along with several of their volatile ozonolysis products (acetaldehyde, butanaI, acetone, acetic acid and formic acid); which were measured at atmospherically relevant concentrations of parts-per-billion (ppbv) during SOA formation in the University of Vermont Environmental Chamber. To the authors' knowledge, this is the first demonstration of the simultaneous, derivatization free analysis of terpenes and their oxygenated ozonolysis products -including reliable quantification of formic acid -in a single chromatographic mass-spectral analysis without the use of custom built or specialty instrumentation.