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  • Writer's pictureBrenna Walsh

Update on SPARTAN sampling

We hope you are well during these uncertain times and that you and your loved ones have been able to stay safe and healthy. Dramatic changes have been occurring in air quality worldwide during the last few weeks and months. Recent expansion of SPARTAN, together with your critical contributions, well position SPARTAN to record these changes. So we are writing to share with you an update with you on recent developments within the network.

In September 2019, SPARTAN became jointly hosted by Dalhousie University and Washington University. New SPARTAN labs at Washington University in St. Louis Missouri are allowing for increased precision of analysis, and expanded analysis performed on SPARTAN filters, allowing for more detailed compositional information from collected samples.

The new laboratory facility is in the Center for Aerosol Science and Engineering, in the department of Energy, Environmental and Chemical Engineering at the McKelvey School of Engineering. We are using a state-of-the-art weighing system for filter pre- and post-weighing, two new Ion Chromatography systems and analysis by x-ray fluorescence. The lab also has space for instrument testing, and we will be deploying instruments to selected new sites from WashU in 2020. Supported by collaborators, supplemental analysis at WashU now includes UV-vis spectroscopy, and the capability for aerosol mass spectroscopy is in development.

Weighing is conducted in a Darwin-Chambers environmentally controlled room. This allows for finer control over temperature and humidity conditions used for weighing, resulting in narrowing the acceptable temperature and humidity conditions to further increase quality of SPARTAN mass measurements. The Mettle Toledo Laboratories (MTL) AH500e weighing and data recording system is paired with the MTL XPR6UD5 microbalance, allowing us to load multiple cartridges worth of filters to increase throughput while maintaining data quality. The filters are picked up in sequence by the carrier arm and weighed automatically in triplicate. This reduces human error and allows for more time for our analysts to perform other analyses. Weighs are also stored automatically in easy to extract analysis logs.

Analysis for water-soluble ions is performed on a pair of Thermo Scientific Dionex Integrion Reagent Free Ion Chromatography (IC) systems. The first is customized for anion analysis and the second for cations. Eluent is generated automatically in each system, which increases sensitivity, improves resolution of the instrument, and increases reproducibility.

X-ray fluorescence (XRF) has recently been added to the SPARTAN analysis protocol as a complimentary technique to Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), used to measure trace element content in filter samples. XRF is a non-destructive technique, and analysis is performed before samples undergo extraction in preparation for IC. Ten filters can be loaded into the sample changer for analysis, and we are currently able to quantify 26 different elements. A Helium line is connected to the instrument to enhance detection of ultra-light elements.

SPARTAN has also begun to tap into some of the expertise of other research groups at WashU. Ultraviolet-visible spectroscopy (UV-Vis), another non-destructive technique is being done on SPARTAN samples for the first time, which will us to determine a more accurate measure of brown carbon content. Professor Rajan Chakrabarty’s group is leading on sample analysis via UV-Vis. A small volume nebulizer is also being built to couple to an existing aerosol mass spectrometer in Professor Brent Williams’ group, following the design developed by Professor Rachel O’Brien. This will allow for measurement and quantification of water-soluble organics from SPARTAN samples.

The SPARTAN network will also be expanding in 2020, with a site which will get up and running shortly in Santiago, Chile as well as several site which will go online as part of NASA’s MAIA project.

Though some operations have slowed due to restrictions which have been put in place to stop the spread of COVID-19, site operators at our sites have been continuing to sample when possible, and we would like to pass along particular thanks for their work, especially during this time. Thank you all for your continued interest in SPARTAN, and looking forward to continued collaboration.

Brenna Walsh

SPARTAN Project Manager

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Mar 11, 2021

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