Solid-phase excitation-emission matrix spectroscopy for chemical analysis of combustion aerosols

Abstract

Exposure to ultrafine combustion aerosols such as particulate matter (PM) from residential woodburning, forest fires, cigarette smoke, and traffic emission have been linked to adverse health outcomes. Excitation-emission matrix (EEM) spectroscopy presents a sensitive and cost-effective alternative for analysis of PM organic fraction. However, as with other analytical chemistry methods, the miniaturization is hindered by a solvent extraction step and a need for benchtop instrumentation. We present a methodology for collecting and in-situ analysis of airborne nanoparticles that eliminates labor-intensive sample preparation and miniaturizes the detection platform. Nanoparticles are electrostatically collected onto a transparent substrate coated with solid-phase (SP) solvent—polydimethylsiloxane (PDMS). The PM organic fraction is extracted into PDMS and analyzed in-situ, thus avoiding liquid-phase extraction. In the SP-EEM analysis, we evaluated external and internal excitation schemes. Internal excitation shows the lowest scattering interference but leads to signal masking from PDMS fluorescence for λ<250nm. The external excitation EEM spectra are dependent on the excitation light incident angle; ranges of 30–40° and 55–65° show the best results. SP-EEM spectra of woodsmoke and cigarette smoke samples are in good agreement with the EEM spectra of liquid-phase extracts. The SP-EEM technique can be used to develop wearable sensors for exposure assessments and environmental monitoring.

Temperature-Dependent Molecular Evolution of Biochar-Derived Dissolved Black Carbon and Its Interaction Mechanism with Polyvinyl Chloride Microplastics

“…The low RSD of peak intensities from fluorescence measurements of SRFA indicated good repeatability/stability of instruments according to the reported analyses . The inner filter effect and scattering correction and parameter calculation of EEM are shown in the SI.…”

“…The low RSD of peak intensities from fluorescence measurements of SRFA indicated good repeatability/stability of instruments according to the reported analyses. 50 The inner filter effect and scattering correction and parameter calculation of EEM are shown in the SI. PARAFAC was conducted based on 21 EEM datasets of DBCs before and after MP PVCinteraction using the drEEM toolbox with MATLAB, 51−53 which was validated by an explained variance of >99.4% and split-half validation of random halves.…”