No abstract

No abstract

Chlorinated paraffins (CPs) are a class of compounds that are currently produced and used in large amounts in commercial products worldwide. In this study, food, indoor air, indoor dust, and drinking water samples were collected to evaluate the external exposure levels of CPs and possible pathway for the general population in Beijing, China. Short chain CPs (SCCPs) and medium chain CPs (MCCPs) in 199 samples were analyzed using a gas chromatography tandem time-of-flight high-resolution mass spectrometry (GC-TOF-HR-MS) method. High levels of CPs were observed in the indoor environment from residential houses, offices, and student dormitories. The geometric mean concentrations (GM) of ∑SCCPs and ∑MCCPs in indoor dust were 92 μg g and 82 μg g, respectively, while in indoor air, the concentrations were 80 ng m and 3.4 ng m, respectively. The GM of ∑SCCPs and ∑MCCPs in the diet were 83 ng g dry weight (dw) and 56 ng g dw, respectively. The most important external exposure routes to CPs to the general populations in Beijing were food intake and indoor dust ingestion. Indoor dust and indoor air posed higher risks for toddlers and infants than for adults.

Six coker gas oils (CGOs) and three basic fractions extracted from one of the CGOs by 0.1, 0.4, and 1 M HCl hydrochloric acid were characterized by positive-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) and compared to those analyzed by gas chromatography mass spectrometry (GC-MS). The ultra high mass resolving power and high mass accuracy of FT-ICR MS allow the assignment of a unique elemental composition to each peak in the mass spectrum. Basic nitrogen species were characterized by class, type, and carbon number. The mass spectra of the CGOs at the 200-500 Da mass range were similar, but the distribution of double bond equivalence (DBE) versus carbon number were different. Among the N, N 2 , NO, and NS that were identified in CGOs, the N class nitrogen species were dominant. The results showed that hydrotreating reduced the relative abundance of all class species, except for the N class species. This suggests that some N class species are refractory to hydrotreating. The molecular weight of nitrogen species in the acid-extracted basic nitrogen fraction of CGO was lower than that of its parent CGO. The N 3 , NO 2 , and N 2 O class species were clearly identified and concentrated in the basic nitrogen fraction, but were not detected in their parent CGO. The N class species with ring plus DBE value of 4-16 in the basic nitrogen fraction were also identified by GC-MS analysis.