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Non-targeted analysis (NTA) methods are being increasingly used to aid in the identification of unknown compounds in the environment, a problem that has challenged environmental chemists for decades. Despite its increased use, quality assurance practices for NTA have not been well established. Furthermore, capabilities and limitations of certain NTA methods have not been thoroughly evaluated. Standard reference material dust (SRM 2585) was used here to evaluate the ability of NTA to identify previously reported compounds, as well as a suite of 365 chemicals that were spiked at various stages of the analytical procedure. Analysis of the unaltered SRM 2585 extracts revealed that several previously reported compounds can be identified by NTA, and that correct identification was dependent on concentration. A manual inspection of unknown features in SRM 2585 revealed the presence of two chlorinated and fluorinated compounds in high abundance, likely precursors to perfluorooctane sulfonate (PFOS) and perfluorohexane sulfonate (PFHxS). A retrospective analysis of data from the American Healthy Homes Survey revealed that these compounds were present in 42% of sampled homes. Spiking the dust at various stages of sample preparation revealed losses from extraction, cleanup, and instrumental analysis; the log Kow for individual compounds influenced the overall recovery levels but no pattern could be discerned from the various degrees of interference that the matrix had on the ionization efficiency of the spiked chemicals. Analysis of the matrix-free chemical mixture at low, medium, and high concentrations led to more correct identifications than analysis at one, very high concentration. Varying the spiked amount and identifying reported compounds at known concentrations allowed an estimation of the lower limits of identification (LOIs) for NTA, analogous to limits of detection in targeted analysis. The LOIs were much lower than levels in dust that would be likely to cause bioactivity in humans, indicating that NTA is useful for identifying and monitoring compounds that may be of toxicological concern.

A method for the analysis of short-chain and medium-chain chlorinated paraffins (SCCPs and MCCPs) in house dust was developed. The method is based on sonication extraction, sample cleanup by solid phase extraction (SPE), and separation and detection by gas chromatography coupled with mass spectrometry (GC/MS) operated in electron capture negative ion (ECNI) chemical ionization mode. The method is sensitive, with method detection limits (MDLs) down to 0.22 μg/g for SCCPs and 0.55 μg/g for MCCPs. The overall recoveries of the method were 104 (± 11)% and 108 (± 16)% for SCCPs and MCCPs, respectively. The method was successfully applied to the analysis of SCCPs and MCCPs in NIST standard reference material (SRM 2585, organic contaminants in house dust) and a subset of house dust samples collected under the Canadian House Dust Study (CHDS). Average concentrations of SCCPs and MCCPs in SRM 2585 ( n  = 12 replicates) were 7.58 (± 0.43) μg/g for SCCPs and 16.4 (± 2.1) μg/g for MCCPs, respectively. A comparison was made between CP concentrations in paired dust samples collected using two different methods from the same homes: fresh or “active” dust (FD) collected by technicians and a sample taken from the household vacuum cleaner (HD). Spearman rank analysis showed a significant positive correlation ( p  < 0.01) between FD and HD samples for both MCCPs and SCCPs. CPs were detected in every house dust sample ( n  = 48 HD samples), with median (range) concentrations of 6.2 (4.0 - 57) μg/g and 19 (5.9-901) μg/g for SCCPs and MCCPs, respectively. Widely scattered CP levels and 100% detection frequency in this preliminary set of 48 HD samples suggest a wide variability in Canadian household exposures to CPs.

Standard Reference Material® (SRM®) 2585 can be considered as a model sample of settled indoor dust. At least 168 adsorbed chemicals were identified and quantified, generating a complex and potentially toxic mixture. Inhalable fractions PM10 and PM2.5 were isolated and compared to SRM® 2585 for their intrinsic properties and their respiratory toxicity using pertinent normal human bronchoepithelial (NHBE) cells. The intrinsic oxidative potential (OP) of SRM® 2585 and its subfractions was measured in acellular conditions, together with ROS generation and endotoxin content. For SRM® 2585 and PM10, cellular responses were evaluated on NHBE cells after 72 h exposure (1.1 to 110 µg/mL). The presence of endotoxins associated with an intrinsic prooxidant potential did not lead to the induction of an inflammatory response. Interestingly, cytokine production was decreased, strongly for IL-1β and to a lesser extent for IL-6. Only PM10 induced an acute toxicity. In parallel, mutagenicity was evaluated from organic extracts. Mutagenic profiles indicated the concomitant presence of nitro-PAHs in addition to the previously reported PAHs. This could be of concern for long-term health effects in a context of chronic exposure.

An analytical method was developed for the measurement of 18 novel halogenated flame retardants in house dust. Sample preparation was based on ultrasound-assisted solvent extraction and clean up with solid phase extraction (SPE). Sample extracts were analyzed by gas chromatography-mass spectrometry (GC/MS) operated in electron capture negative ion (ECNI) chemical ionization mode. Baseline data from 351 fresh (active) dust samples collected under the Canadian House Dust Study (CHDS) revealed that five out of 18 target chemicals were present with detection frequencies higher than 90 %. Median (range) concentrations for these five compounds were as follows: 104 (<1.5–13,000) ng/g for 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTBB), 8.5 (<1.7–2390) ng/g for 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), 10.2 (<1.7–430) ng/g for hexabromobenzene (HBB), 2.9 (<1.2–1410) ng/g for syn -dechlorane plus ( syn -DP) and 5.6 (<1.9–1570) ng/g for anti -dechlorane plus ( anti -DP). A comparison of two sampling methods in a subset of 40 homes showed significant positive correlations between samples of “active” dust and samples taken directly from the household vacuum cleaner for all target compounds having median values above their corresponding method detection limits (MDLs). In addition, the method was also applied to the analysis of the targeted compounds in National Institute of Standards and Technology (NIST) standard reference material (SRM 2585, organic contaminants in house dust). Results from the current study could contribute to the potential certification of target chemicals in SRM 2585.