Quantification of Element Mass Concentrations in Ambient Aerosols by Combination of Cascade Impactor Sampling and Mobile Total Reflection X-ray Fluorescence Spectroscopy

Abstract

Quantitative chemical analysis of airborne particulate matter (PM) is vital for the understanding of health effects in indoor and outdoor environments, as well as for enforcing EU air quality regulations. Typically, airborne particles are sampled over long time periods on filters, followed by lab-based analysis, e.g., with inductively coupled plasma mass spectrometry (ICP-MS). During the EURAMET EMPIR AEROMET project, cascade impactor aerosol sampling is combined for the first time with on-site total reflection X-ray fluorescence (TXRF) spectroscopy to develop a tool for quantifying particle element compositions within short time intervals and even on-site. This makes variations of aerosol chemistry observable with time resolution only a few hours and with good size resolution in the PM10 range. The study investigates the proof of principles of this methodological approach. Acrylic discs and silicon wafers are shown to be suitable impactor carriers with sufficiently smooth and clean surfaces, and a non-destructive elemental mass concentration measurement with a lower limit of detection around 10 pg/m3 could be achieved. We demonstrate the traceability of field TXRF measurements to a radiometrically calibrated TXRF reference, and the results from both analytical methods correspond satisfactorily.

Size distribution and relationship of airborne SARS-CoV-2 RNA to indoor aerosol in hospital ward environments

“…Cut-off diameters below 1 µm were verified through a comparison measurement using an aerosol spectrometer 36 . Total particle mass agreed well with reference filter sampling and size distributions were found to be similar to those obtained using a commercial Dekati impactor 37 . The sampling time was 8 h in both cases, during daytime including the main time for medical interventions.…”

Traceable Characterization of Nanomaterials by X-ray Spectrometry Using Calibrated Instrumentation

“…Engineered nanoparticles, often having small size distributions, are ideal nanoobjects to be characterized by GIXRF [27] with respect to surface coverage and particle composition. With respect to characterizations of nanoparticles and environmental aerosols, both TXRF [25] and GIXRF [26] have shown their analytical capabilities to quantify elemental mass depositions of size-fractionated nano-and microparticles collected by means of cascade impactors on flat substrates. A reference-free GIXRF quantification mode [26] allows one to determine the angular ranges of validity for the correct quantification of specific elemental mass depositions.…”

“…Besides revealing information about elemental mass depositions and related chemical binding states of nanomaterials by means of XRF and XAFS, complementary chemical information can be revealed using high-resolution X-ray emission spectrometry (XES), which often provides a different discrimination capability depending on the specific With respect to characterizations of nanoparticles and environmental aerosols, both TXRF [25] and GIXRF [26] have shown their analytical capabilities to quantify elemental mass depositions of size-fractionated nano-and microparticles collected by means of cascade impactors on flat substrates. A reference-free GIXRF quantification mode [26] allows one to determine the angular ranges of validity for the correct quantification of specific elemental mass depositions.…”

X-ray fluorescence spectrometry for environmental analysis: Basic principles, instrumentation, applications and recent trends

“…In this sense, Prost et al (2017) demonstrated that the direct collection of aerosol particles on greased quartz reflectors using a PM10 impactor, reduce the risk of contamination and samples can be measured directly and undiluted. In a recent publication, acrylic glass discs and silicon waters were shown to be suitable carriers, with sufficiently smooth and clean surfaces, for TXRF analysis of PM as well (Seeger et al, 2021). Finally, in addition to PM characterization, TXRF has also been used to determine the concentration of airborne Hg (Böttger et al, 2020).…”