Aerosolomics based approach to discover source molecular markers: A case study for discriminating residential wood heating vs garden green waste burning emission sources.

Biomass burning is a significant source of particulate matter (PM) in ambient air and its accurate source apportionment is a major concern for air quality. The discrimination between residential wood heating (RWH) and garden green waste burning (GWB) particulate matter (PM) is rarely achieved. The objective of this work was to evaluate the potential of non-targeted screening (NTS) analyses using HRMS (high resolution mass spectrometry) data to reveal discriminating potential molecular markers of both sources. Two residential wood combustion appliances (wood log stove and fireplace) were tested under different output conditions and wood moisture content. GWB experiments were carried out using two burning materials (fallen leaves and hedge trimming). PM samples were characterized using NTS approaches with both LC- and GC-HRMS (liquid and gas chromatography-HRMS). The analytical procedures were optimized to detect as many species as possible. Chemical fingerprints obtained were compared combining several multivariate statistical analyses (PCA, HCA and PLS-DA). Results showed a strong impact of the fuel nature and the combustion quality on the chemical fingerprints. 31 and 4 possible markers were discovered as characteristic of GWB and RWH, respectively. Complementary work was attempted to identify potential molecular formulas of the different potential marker candidates. The combination of HRMS NTS chemical characterization with multivariate statistical analyses shows promise for uncovering organic aerosol fingerprinting and discovering potential PM source markers.

Analysis of BTEX and chlorinated solvents in meconium by headspace-solid-phase microextraction gas chromatography coupled with mass spectrometry.

Meconium is the earliest stool of newborns, and is a complex matrix that reflects the degree of exposure of the fetus to xenobiotics. To investigate fetal exposure to volatile organic compounds, an analytical method was developed to identify and quantify BTEX (benzene, toluene, ethylbenzene, and o,m,p-xylene) and two chlorinated solvents (trichloroethylene and tetrachloroethylene) in meconium. Headspace-solid-phase microextraction coupled with gas chromatography-mass spectrometry was selected because it is simple, sensitive, can be automated, and requires no extensive sample preparation. Several extraction variables were optimized (fiber type, incubation time, temperature of fiber, and use of salt). Because meconium is a complex matrix, quantification by SPME was considered carefully because of potential interference, for example competitive adsorption. Calibration in water was compared with calibration in meconium using external and internal methods (with isotope-labeled compounds). In meconium, limits of quantification were determined to be in the range 0.064-0.096 ng g(-1) for the investigated compounds. All target compounds were determined in "real-case" meconium samples.