Measuring the oxygen content of atmospherically relevant compounds using a novel, robust detection approach.

Organic aerosols have important impacts on visibility, human health and local and global climate, with the chemical composition of the particles strongly influencing these effects. In particular, oxygen content controls the tendency of particles to form clouds and may also drive adverse health effects. Currently, methods for ascertaining the chemical composition of aerosols depend on either filter-based measurements or real-time measurements with advanced mass spectrometers. The former does not provide real time-data, whereas the latter is expensive and requires highly-trained on-site personnel. There is thus a need for a robust, low-maintenance instrument which can provide real-time measurements of aerosol chemical composition.

We demonstrate here a novel approach that combines multiple robust, field-deployable, moderate-cost detectors to quantify the carbon and oxygen content of analytes. We coupled our detector to a gas chromatograph for analysis of individual analytes from complex mixtures such as air fresheners and perfumes and analyzed highly-oxygenated compounds without chromatographic separation. We are able to estimate the oxygen-to-carbon ratio of atmospherically-relevant analytes to within 10% across the O:C range of 0 to 1. Sensitivity of this approach is expected to allow measurements of the concentration and O:C of sample loadings on the order of 100 ng. This detection technique is proposed as a method to allow for robust, field-deployable characterization of ambient organic aerosols at levels on the order of μg/m³ with hourly time resolution.