Development of a method for measuring organic compounds in ice samples using PTR-ToF-MS

Abstract

The uncertainty of the past aerosol composition affects the reliability of estimates made of their effect on Earth's radiation budget. In this report, a method to measure organic compounds in ice samples by using a Proton-Transfer-Reaction Time-of-Flight Mass-Spectrometer (PTR-ToF-MS) will be presented. A "PTR-ice" device has been developed to separate soluble and insoluble organics and to remove bulk water from the samples prior to the analysis with PTR-ToF-MS. The "PTR-ice" system has been validated and compared with offine TD-PTR-MS measurements [Timkovsky et al., 2014] of ambient filter samples from the CESAR-observatory near Cabauw, Netherlands. Improvements in bulk water removal was obtained by using evaporation through a dry air flow instead of extracting moisture by creating a vacuum. Artefacts resulting from the rather large inner surface of the "PTR-ice" are demonstrated and useful insights have been gained on how to reduce these. A definite measurement method has yet to be found, however improvements on the measurement of organic compounds in ice samples are shown.