Huiting Huang

A Novel Method for Profiling and Quantifying Short- and Medium-Chain Chlorinated Paraffins in Environmental Samples Using Comprehensive Two-Dimensional Gas Chromatography–Electron Capture Negative Ionization High-Resolution Time-of-Flight Mass Spectrometry

Chlorinated paraffins (CPs) are complex technical mixtures containing thousands of isomers. Analyzing CPs in environmental matrices is extremely challenging. CPs have broad, unresolved profiles when analyzed by one-dimensional gas chromatography (GC). Comprehensive two-dimensional GC (GC×GC) can separate CPs with a high degree of orthogonality. A novel method for simultaneously profiling and quantifying short- and medium-chain CPs, using GC×GC coupled with electron capture negative ionization high-resolution time-of-flight mass spectrometry, was developed. The method allowed 48 CP formula congener groups to be analyzed highly selectively in one injection through accurate mass measurements of the [M - Cl](-) ions in full scan mode. The correlation coefficients (R(2)) for the linear calibration curves for different chlorine contents were 0.982 for short-chain CPs and 0.945 for medium-chain CPs. The method was successfully used to determine CPs in sediment and fish samples. By using this method, with enhanced chromatographic separation and high mass resolution, interferences between CP congeners and other organohalogen compounds, such as toxaphene, are minimized. New compounds, with the formulas C9H14Cl6 and C9H13Cl7, were found in sediment and biological samples for the first time. The method was shown to be a powerful tool for the analysis of CPs in environmental samples.

Health risks posed to infants in rural China by exposure to short- and medium-chain chlorinated paraffins in breast milk

Chlorinated paraffins (CPs) are complex mixtures of synthetic chemicals found widely in environmental matrices. Short-chain CPs (SCCPs) are candidate persistent organic pollutants under the Stockholm Convention. There should be great concern about human exposure to SCCPs. Data on CP concentrations in human breast milk is scarce. This is the first study in which background SCCP and medium-chain CP (MCCP) body burdens in the general rural population of China have been estimated and health risks posed to nursing infants by CPs in breast milk assessed. The concentrations of 48 SCCP and MCCP formula congeners were determined in 24 pooled human milk samples produced from 1412 individual samples from eight provinces in 2007 and 16 provinces in 2011. The samples were analyzed by comprehensive two-dimensional gas chromatography electron capture negative ionization high-resolution time-of-flight mass spectrometry. The median SCCP and MCCP concentrations were 303 and 35.7ngg-1 lipid weight, respectively, for the 2007 samples and 360 and 45.4ngg-1 lipid weight, respectively, for the 2011 samples. The C10 and C14 homologs were the dominant CP carbon-chain-length groups, contributing 51% and 82% of the total SCCP and MCCP concentrations, respectively. There are probably multiple CP sources to the general Chinese population and numerous exposure pathways. The median estimated daily SCCP and MCCP intakes for nursing infants were 1310 and 152ngkg-1d-1, respectively, in 2007 and 1520 and 212ngkg-1d-1, respectively, in 2011. SCCPs do not currently pose significant risks to infants in China. However, it is necessary to continuously monitor CP concentrations and health risks because CP concentrations in Chinese human breast milk are increasing.

Short- and medium-chain chlorinated paraffins in sediments from the middle reaches of the Yangtze River: Spatial distributions, source apportionment and risk assessment

Chlorinated paraffins (CPs) are easily adsorbed into sediments where they pose potential risks to the ecosystem and human health. Few studies have investigated short- and medium-chain CPs (SCCPs and MCCPs) in sediments. The aim of the present study was to comprehensively investigate contamination levels, spatial distributions, sources and risks posed by CPs in sediments from the middle reaches of the Yangtze River. The sediment samples were analyzed by two-dimensional gas chromatography coupled with time-of-flight mass spectrometry (GC×GC-TOFMS). The concentrations of SCCPs and MCCPs ranged from 4.19 to 41.6ng/g dry weight (dw) and not detected to 14.6ng/g dw, respectively. No significant correlation was found between the total organic carbon contents and CP concentrations (P>0.05). The spatial distributions showed that CP contamination levels in the sediments were related to local human activities. The dominant congener groups were C10-11Cl6-7 for SCCPs, and C14Cl7-8 for MCCPs. Correspondence analysis revealed that likely sources of SCCPs were the production and use of CP-42 and CP-52. Principal component analysis indicated that SCCPs and MCCPs in the sediments may come from different sources. Moreover, CPs with nine carbon atoms were quantitated for the first time in sediment samples, and the results indicated they should not be neglected in future analyses. Risk assessments indicated that CPs in the sediments did not pose a great ecological risk currently.

Bioaccumulation and biomagnification of short and medium chain polychlorinated paraffins in different species of fish from Liaodong Bay, North China

Chlorinated paraffins (CPs) are highly complex technical mixtures, and the short chain chlorinated paraffins (SCCPs) are classed as persistent and have been included in the Stockholm Convention. However, there have been few studies of SCCPs and medium chain chlorinated paraffins (MCCPs) and their bioaccumulation and biomagnification in different species of fish. The present study investigated the levels, congener group profiles, bioaccumulation, and biomagnification of SCCPs and MCCPs in different species of fish from Liaodong Bay, North China. The ranges for the ΣSCCP and ΣMCCP concentrations were 376.3–8596 ng/g lipid weight (lw) and 22.37–5097 ng/g lw, respectively. The logarithms of bioaccumulation factors of ΣSCCPs ranged from 4.69 to 6.05, implying that SCCPs bioaccumulated in the fish. The trophic magnification factor of ΣSCCPs was 2.57, indicating that SCCPs could biomagnify in fish. Carbon chain length, the numbers of chlorine atoms, and octanol/water partition coefficients of the SCCPs and MCCPs might be important factors affecting the bioaccumulation of these chemicals in fish. The risk posed to human health by consumption of fish containing SCCPs was low. New SCCPs with nine carbons (C9) were detected in fish in this study.

Short- and medium-chain chlorinated paraffins in aquatic foods from 18 Chinese provinces: Occurrence, spatial distributions, and risk assessment

Short-chain chlorinated paraffins (SCCPs) are classed as persistent organic pollutants and were included in the Stockholm Convention in May 2017. Large amounts of chlorinated paraffins (CPs) are produced in China than in any other countries. CPs can be released into the environment while being produced and used, and can bioaccumulate in aquatic biota and be ingested by humans. Dietary intake is the main route through which humans are exposed to CPs. It has previously been found that persistent organic pollutant concentrations are usually higher in aquatic foods than in other foods. The risk of human exposure to SCCPs in aquatic foods should therefore be of concerns. However, SCCP concentrations in aquatic foods have not been systematically studied. A total of 1620 aquatic food samples were collected, and 18 pooled samples were analyzed by two-dimensional gas chromatography coupled with electron-capture negative-ionization time-of-flight mass spectrometry. The mean SCCP and MCCP concentrations were 1472 and 80.5ng/gwet weight, respectively. The dominant SCCP and MCCP congener groups were C10Cl6-7 and C14Cl7-8, respectively. The concentrations were much higher than those have been found in aquatic foods in other countries. The CP concentrations in the samples consumed by local people from eastern and southern China were higher than the concentrations in samples from central and western China. Risk assessment results indicated that SCCPs and MCCPs in aquatic foods do not pose significant risks to residents of China.

Concentrations and trophic magnification of polychlorinated naphthalenes (PCNs) in marine fish from the Bohai coastal area, China

Polychlorinated naphthalenes (PCNs) have been found widely in the aquatic environment and can be transferred through food chains, which can magnify or dilute their toxic effects on humans. In this study, PCNs were analyzed in samples of 17 species of fish with different dietary habits collected in the Bohai coastal area in China. Dichloronaphthalenes, which have rarely been quantified in previous studies, were determined. The total PCN concentrations were from 7.3 to 214 pg/g wet weight, and the highest concentration was found in ditrema. The trichloronaphthalenes were the most abundant PCNs, followed by the dichloronaphthalenes and pentachloronaphthalenes. The relatively high contributions of the less-chlorinated homologs to the total PCN concentrations indicated that the main PCN sources around the Bohai were industrial thermal process emissions rather than technical PCN formulations. The trophic magnification factors of the PCN homologs were from 3.1 to 9.9, indicating that PCNs were biomagnified by fish. The trophic magnification factor of dichloronaphthalene and trichloronaphthalenes was 5.8 and 6.4, respectively, indicating for the first time that dichloronaphthalene and trichloronaphthalenes can undergo trophic magnification by fish. The two highest trophic magnification factors were for the pentachloronaphthalenes and hexachloronaphthalenes, probably because these PCNs having fewer vicinal carbon atoms without chlorine atoms attached are less easily biotransformed than the other homologs. The dioxin-like toxicities of the PCNs in the samples, expressed as potential toxic equivalences (TEQs), were assessed. The highest total TEQ was 0.0090 pg/g ww, in Pacific herring, and the hexachloronaphthalenes were the dominant contributors to the total TEQs in the fish samples. The PCN TEQs were much lower than the polychlorinated dibenzo-p-dioxin and dibenzofuran and dioxin-like polychlorinated biphenyl TEQs found in fish from the Bohai in previous studies, and made marginal contributions to overall human exposure to dioxin-like TEQs, suggesting that PCNs pose no toxicological concerns.