Congener Groups Research Articles

Initial dietary risk assessment of chlorinated paraffins in edible fungi in Chinese markets.

Dietary intake is one of the main pathways for residents to become exposed to chlorinated paraffins (CPs). In China, due to the popularization of nutritional and medicinal edible fungi, consumption has increased on a yearly basis. Edible fungi have a variety of active substances and are consumed daily by residents. However, there is limited information on the concentration and source of chlorinated paraffins in edible fungi. In this study, the concentrations of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in 105 edible fungi samples and 36 culture material samples were detected. The concentration range of SCCPs was 79.8ng/g dw to 3879.3ng/g dw, and the MCCPs was ND to 572.3ng/g dw. Spearman correlation analysis indicated that the sources of SCCPs and MCCPs in edible fungi were similar (r =0.57, p<0.01). The preponderant SCCPs and MCCPs congener group profiles were C10 Cl7-8 and C14 Cl6-8 . CPs were detected in culture materials, the concentration range of SCCPs was 320.2ng/g dw to 4326ng/g dw, and the MCCPs was 333.4ng/g dw to 4517.4ng/g dw. And the preponderant SCCPs and MCCPs homologues in culture materials were C11-12 Cl6 and C14 Cl6 . The linear discriminant analysis results indicated different contamination models of CPs between edible fungi and culture materials. The mean estimated daily intake values of SCCPs and MCCPs were 308.1ng/kg bw/d and 94.4ng/kg bw/d, respectively, indicating no potential health risk posed by CP exposure in edible fungi.

The toxicological profile of polychlorinated naphthalenes (PCNs).

The legacy of polychlorinated naphthalenes (PCNs) manufactured during the last century continues to persist in the environment, food and humans. Metrological advances have improved characterisation of these occurrences, enabling studies on the effects of exposure to focus on congener groups and individual PCNs. Liver and adipose tissue show the highest retention but significant levels of PCNs are also retained by the brain and nervous system. Molecular configuration appears to influence tissue disposition as well as retention, favouring the higher chlorinated (≥ four chlorines) PCNs while most lower chlorinated molecules readily undergo hydroxylation and excretion through the renal system. Exposure to PCNs reportedly provokes a wide spectrum of adverse effects that range from hepatotoxicity, neurotoxicity and immune response suppression along with endocrine disruption leading to reproductive disorders and embryotoxicity. A number of PCNs, particularly hexachloronaphthalene congeners, elicit AhR mediated responses that are similar to, and occur within similar potency ranges as most dioxin-like polychlorinated biphenyls (PCBs) and some chlorinated dibenzo-p-dioxins and furans (PCDD/Fs), suggesting a relationship based on molecular size and configuration between these contaminants. Most toxicological responses generally appear to be associated with higher chlorinated PCNs. The most profound effects such as serious and sometimes fatal liver disease, chloracne, and wasting syndrome resulted either from earlier episodes of occupational exposure in humans or from acute experimental dosing of animals at levels that reflected these exposures. However, since the restriction of manufacture and controls on inadvertent production (during combustion processes), the principal route of human and animal exposure is likely to be dietary intake. Therefore, further investigations should include the effects of chronic lower level intake of higher chlorinated PCN congeners that persist in the human diet and subsequently in human and animal tissues. PCNs in the diet should be evaluated cumulatively with other similarly occurring dioxin-like contaminants.

Semiquantitative Characterization of Bromo-chloro Paraffins and Olefins in the Australian Environment.

A semiquantitative high-resolution mass spectrometry method was developed and applied to assess the occurrence of bromo-/chloro paraffins (BCPs) and olefins (BCOs) in the environment. More than 400 possible BCPs and BCO congener groups were detected in dust, air, and sewage sludge samples collected from Australia. Median chain analytes with the number of halogen atoms <7 (CnHmClxBry, 14 ≤ n ≤ 17, x + y < 7) prevailed in the dust and sludge samples, while short chain analytes (CnHmClxBry, 10 ≤ n ≤ 13, x + y < 7) predominated the air samples. The estimated concentrations of ∑BCPs and ∑BCOs in dust and sludge were approximately 20% that of the chlorinated paraffins (CPs) present, with the median concentrations of 5.4 μg/g (dust) and 0.18 μg/g (sludge) for ∑BCPs and 22 μg/g (in dust) and 0.50 μg/g (sludge) for BCOs. In the air samples, the concentrations of BCPs (0.020 pg/m3) and BCOs (0.032 pg/m3) were 3-4 orders of magnitudes lower than the concentrations of CPs (790 pg/m3). Significant correlations (P < 0.001) were found between the concentration of CPs, BCPs, and BCOs in all the matrices.

Short- and medium-chain chlorinated paraffins in honey from China: Distribution, source analysis, and risk assessment

Chlorinated paraffins (CPs) are industrial chemicals produced in large quantities. Short-chain CPs (SCCPs) were classified as persistent organic pollutants under the Stockholm Convention in 2017. Medium-chain CPs (MCCPs) became candidate persistent organic pollutants in 2021. CPs are now ubiquitously found in the environment. Honey bees can be exposed to CPs during foraging, and this exposure subsequently results in the contamination of honey and other bee products along with colony food production and storage. Here, SCCP and MCCP concentrations in honey collected from Chinese apiaries in 2015 and 2021 were determined. Total CP concentrations in honey from 2021 to 2015 were comparable, but the ratio of MCCPs/SCCPs was higher in 2021 than in 2015. SCCP and MCCP congener group profiles in all honey samples were similar and dominated by C10–11Cl6–7 and C14Cl6–7, respectively. MCCP concentrations were also higher than SCCP concentrations in bees, pollen, and wax but not in bee bread, which were all collected in 2021. The order of average CP concentrations was determined as wax > bee > pollen > bee bread > honey. Poor relationships were found between SCCP concentrations in honey and other samples, but a relationship between MCCP concentrations in honey and other samples was observed. Migration tests of CPs in plastic bottles showed essentially no migration into honey during storage. The risks to humans from CPs in honey are low.

Air–soil exchange of and risks posed by short- and medium-chain chlorinated paraffins: Case study in a contaminated area in China

Short-chain (SC) and medium-chain (MC) chlorinated paraffins (CPs) are found widely in the environment. Little research into air–soil exchange of SCCPs and MCCPs has been performed. In this study, CP concentrations, congener group profiles, and air–soil exchange in a typical contaminated area were investigated. A total of 10 soil samples and 10 air samples were collected from Zhoushan, an island in China. The samples were analyzed by two-dimensional gas chromatography electron capture negative ionization mass spectrometry. The SCCP and MCCP concentrations in the soil samples were 72–3842 and 117–8819 ng/g, respectively, and the SCCP and MCCP concentrations in the air samples were 57–208 and 1.8–25 ng/m3, respectively. The highest CP concentrations in both soil and air were found in samples from near shipyards, possibly because of CPs being emitted from metal cutting fluids and marine paints used at the shipyards. C14–15Cl7-9 were the dominant CP congener groups in the soil samples. C10Cl6–7 were the dominant CP congener groups in the air samples. Chlorinated decane and undecane and penta-, hexa-, and hepta-chlorinated CPs were enriched in the air relative to the soil. These congeners may have been released from the commercial CP-42 and CP-52. The fugacity fractions (ffs) of 48 homologs decreased as Koa increased. The ffs indicated that SCCPs and MCCPs dominated deposition. The net air–soil exchange fluxes of CPs were 201–769 ng/(m2·h). A preliminary risk assessment indicated that CPs pose low ecological risk except at sampling site S7 and do not pose significant health risks.

Temporal Trends of Persistent Organic Pollutants in Sarasota Bay Common Bottlenose Dolphins (Tursiops truncatus)

Legacy persistent organic pollutants (POPs) were measured in blubber samples collected from 196 common bottlenose dolphins (Tursiops truncatus) from 2000 to 2016 in the Sarasota Bay, Florida, ecosystem. Legacy POPs included polychlorinated biphenyl congeners (ΣPCB; sum of 37 congeners or congener groups), dichloro-diphenyl-trichloroethane (DDT) and transformation products (ΣDDT), chlordane and related compounds (ΣChlor), mirex, polybrominated diphenyl ether congeners (ΣPBDE, sum of five congeners), dieldrin and hexachlorobenzene (HCB). All POP compounds or compound groups declined in dolphin blubber over the study period. POP classes declined at different rates within classifications (sex, adult or calf). For example, dieldrin decline in male dolphins was greatest (−13% per year) while HCB decline was lower (−6.3% per year). For individual POP classes, rates of decline depended on classification. For example, ΣPCB, the POP class present at the highest concentration relative to other POPs, declined at −8.4, −7.8, and −5.6% per year in adult females, adult males and calves, respectively. Overall POP declines were highest in adult males and lowest in calves. Declines in POP concentration with time based on individual dolphins resampled at different time points were consistent with declines calculated based on yearly or biennial cross-sections taken from 2000 through 2016. Overall rates of decline in Sarasota Bay bottlenose dolphins were like declines seen for Great Lakes fish and about twice the rate of decline observed in arctic temporal trend data sets. POP trends appear to have leveled off since 2009 in Sarasota Bay dolphins. For example, ΣPCBs in calves appear to have stabilized at 21 mg/kg lipid. Recent published work on delphinids with blubber concentrations spanning those observed in the present work suggest that levels of legacy POPs currently observed in Sarasota dolphins may suppress population growth. Results from this study confirm the need for continued monitoring of POPs in the Sarasota Bay bottlenose dolphin population to see if concentrations are continuing to fall or have indeed plateaued.

Short- and medium-chain chlorinated paraffins in commercial complementary baby food produced in different European countries: Occurrence, congener group profiles, portion-based dietary intake, and risk assessment

This study was performed to evaluate the presence of chlorinated paraffins (CPs) in complementary baby food from different European countries, to assess portion-based dietary intake of CPs, and to characterize possible risks to children arising from CPs uptake. In total, 86 baby food samples from 22 countries were grouped into eight food-type categories considering the WHO classification. In six out of eight sample categories, predominance of medium-chain CPs (MCCPs) concentrations over short-chain CPs (SCCPs) was observed and, contrary to expectations, samples that contained ingredients of animal origin (e.g., meat or fish) did not display elevated CPs levels. The median ∑CPs concentrations for selected sample categories ranged from 0.8 ng g−1 for desert to 2.8 ng g−1 found in dry cereal and porridge subgroups, while the highest CPs concentration of 387 ng g−1 was observed in dry porridge. Among the selected groups of baby foods, portion-based intake of ∑CPs varied from 1.0 to 43.6 ng kg−1 body weight (b.w.) while exposure estimations indicated that portion-based dietary exposure through consumption of complementary baby food was the highest for infants aged 3–12 months due to the lower body weight. The risk characterization according to the European Food Safety Authority (EFSA) approach showed that the margin of exposure (MOE) figures higher than the critical value for ∑CPs, indicating that the dietary exposures through consumption of complementary baby food are unlikely to be of significant health concern for children. However, it should be pointed out that the performed risk assessment covered only SCCPs and MCCPs, while the occurrence of other groups from CPs and CPs related compounds (e.g., very short-chain CPs, chlorinated alkenes, or long-chain CPs (LCCPs)) was not addressed.

Concentrations, homolog profiles, and risk assessment of short- and medium-chain chlorinated paraffins in soil around factories in a non-ferrous metal recycling park

Chlorinated paraffins (CPs) are used as additives in metal processing in the metal smelting industry. Data on CPs in the environment near metal smelting plants are limited. The objectives of this study were to investigate the concentrations and congener profiles of CPs in soil around factories in a non-ferrous metal recycling park located in Hebei, China, and to investigate human exposure to CPs in the soil. The concentrations of short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) were determined by two-dimensional gas chromatography with electron capture negative ionization mass spectrometry. The SCCP and MCCP concentrations in the soil samples were 121–5159 ng/g and 47–6079 ng/g, respectively. Generally, the CP concentrations in soils around the factories were relatively high compared with those near other contaminated sites and in rural and urban areas. There were significant correlations between the MCCP concentrations, some SCCP carbon homologs, and the total organic carbon content (p < 0.05). The major SCCP and MCCP congener groups were C10Cl6–7 and C15–16Cl5, respectively. Hierarchical cluster analysis and principal component analysis indicated that SCCPs and MCCPs in the soil might originate from extreme pressure additives containing CP-42 and CP-52 and CP-containing waste material from the factories. The concentrations in two samples collected near a metal recycling factory posed a moderate risk according to a risk assessment conducted using risk quotients. Further risk assessment showed that the CPs concentrations in soil did not pose significant health risks to either children or adults.

Short- and medium-chain chlorinated paraffins in soil from an urban area of northern China: Levels, distribution, and homolog patterns

Short-chain chlorinated paraffins (SCCPs) are persistent organic pollutants that are present in relatively high concentrations in various environmental media in China. Many studies have focused on chlorinated paraffins in soil from agricultural land and contaminated areas. There are limited data on the levels of chlorinated paraffins in soil from urban areas. In this study, to investigate the levels, distribution, and homolog patterns of chlorinated paraffins (CPs) in soil from a typical urban area, 130 soil samples were collected and combined to form 26 pooled samples. The samples were analyzed for 50 CP congener groups (C9–17Cl5–10). The concentration ranges for SCCPs, medium-chain CPs (MCCP), and chlorinated nonane paraffin (C9-CP) were 19–1456 ng/g (average: 234 ng/g), <10–385 ng/g (average: 54 ng/g), and 1–39 ng/g (average: 11 ng/g), respectively. The CP concentrations were not significantly correlated with the total organic carbon content (P > 0.05). Compared with other areas worldwide, the SCCP and C9-CP concentrations in soil in this area were at the medium level, and the concentrations of MCCPs were at a low level. The CP concentrations were higher in soil samples collected near factories and domestic garbage disposal sites. C10Cl6–7 were the main SCCP homologs and C14Cl7–8 were the main MCCP homologs. Principal component analysis showed that the sources of C9-CPs, SCCPs, and MCCPs in the soils were similar. Risk assessment showed that the concentrations of SCCPs and MCCPs in soil in this area did not pose a significant risk to soil organisms or human health.

Chloride-attachment atmospheric pressure photoionisation for the determination of short-chain chlorinated paraffins by gas chromatography-high-resolution mass spectrometry

In this work, a new gas chromatography-high-resolution mass spectrometry (GC-HRMS) method based on atmospheric pressure photoionisation (APPI) has been developed for the accurate determination of short-chain chlorinated paraffins (SCCPs) as a reliable alternative to the established methods. To the best of our knowledge, this is the first time these compounds has been analysed by GC-MS using atmospheric pressure photoionisation (APPI). Efficient ionisation of SCCPs was achieved using the new GC-APPI source by the formation of [M+Cl]– adduct ions in negative ion mode using dopant-assisted APPI with a mixture of acetone/CCl4 (3:1, v/v). Operating at a resolution of 70,000 FWHM (full width at half maximum) and monitoring the [M+Cl]– adduct ions for each congener group, a selective determination of the SCCPs was achieved, avoiding isobaric interferences between homologue groups with different carbon chain length and chlorination degree. Moreover, the GC-APPI-HRMS response of each congener group was mainly influenced by its concentration and did not depend on the number of chlorine atoms in the molecule as occurs with the GC-MS methods based on the electron-capture negative ionisation (ECNI). Thus, the contribution of the different carbon and chlorine homologue groups in the SCCP mixtures was determined by the internal normalization method, and the quantification was performed independently of the chlorine content of the SCCP standard mixture employed. The developed GC-APPI-HRMS method offers some interesting advantages over the existing methods, particularly the possibility to quantify individual SCCP congener groups, the use of a simple calibration method for quantification, and an important time-saving in the data processing, especially over ECNI-based traditional methods. The GC-APPI-HRMS method allowed the determination of SCCPs at low concentration levels in fish samples with low method limits of detection (17–34 pg g−1 wet weight for total SCCPs), good precision (RSD < 7%) and trueness (relative error < 8%) and can be proposed as a reliable alternative of the established methods for the determination of these pollutants in environmental samples.

Direct measurements and modeling of congener group specific vapor pressure for chlorinated paraffins

Chlorinated Paraffins (CPs) are a complex group of manmade chemicals detected widely in the environment. To predict their environmental fate and effects, it is important to understand their physical-chemical properties including vapor pressure. In this study, the first direct measurements of the vapor pressure for CP congener groups (C10–16Cl4–11) are presented. Vapor pressure was measured above three industrial CP mixtures with different congener distributions between 20 and 50 °C using a gas saturation method. The measured saturated vapor pressure (P∗) decreased with increasing carbon chain length and Cl content. ΔHvap ranged between 73 and 122 kJ mol−1, consistent with data from the literature and model prediction. The experimental log P∗ at 25 °C agreed well with predictions from an empirical regression model in the literature (R2 = 0.97; RSME = 0.25) and with those predicted from the COSMO-RS-trained fragment contribution model (R2 = 0.95; RSME = 0.35). A new empirical model was calibrated with the P∗ data for 35 congener groups measured in this study. Predicted log P∗ values correlate well with field-measured gas/particle partition coefficients and may therefore be used for estimating the environmental fate and pathways of a broad range of CPs in the environment.

Occurrences, congener group profiles, and risk assessment of short- and medium-chain chlorinated paraffins in cup instant noodles from China

Dietary intake is an important route of human exposure to chlorinated paraffins (CPs). Cup instant noodles are widely popular food and millions packet of instant noodles are consumed every year. To investigate the levels, congener groups, and health risk of SCCPs and MCCPs in each component of cup instant noodles, samples of nine common brands were collected and analyzed by comprehensive two dimensional gas chromatography coupled with mass spectrometry. The mean concentrations in the noodles were 1.2 × 103 ng/g wet weight (ww) (SCCPs) and 1.2 × 102 ng/g ww (MCCPs), the mean concentrations in the seasoning were 1.4 × 103 ng/g ww (SCCPs) and 1.3 × 102 ng/g ww (MCCPs), and the mean concentrations in the soup were 5.6 × 102 ng/L (SCCPs) and 5.4 × 102 ng/L (MCCPs). The SCCP to MCCP ratio were similar in the soup and soup container, which means CPs in the soup might be migrated from the soup container. Seasoning and noodles from the same brands have similar congener profiles of SCCPs and MCCPs, which may be raised from the manufacturing process or food packaging materials. The dominant SCCP congener groups were C10–11Cl6–7 in noodles and seasoning, and C10,13Cl6–7 in soup. The dominant MCCP congener groups were C14–15Cl6–7 in noodles and seasoning, and C14–15Cl6–7 in soup. A preliminary health risk assessment indicated that the current intakes of SCCPs and MCCPs through cup instant noodles in China did not pose a significant risk to human health.

Levels and Risk Assessment of Short and Medium-Chain Chlorinated Paraffins in Soil from Paper Mill Area

Short-chain chlorinated paraffins are persistent organic pollutants, and chlorinated paraffins were widely used as sizing agent in the paper industry. In order to investigate the levels and risk assessment of short-chain and medium-chain chlorinated paraffins in the paper mill plant, the surface soil and soil of different depths were collected.The concentrations, congener group profiles of short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs) in soil were determined by two-dimensional gas chromatography coupled with electron capture-negative ion mass spectrometry. The SCCPs and MCCPs concentrations were 42-3853 ng·g-1 and 34-2091 ng·g-1. The chlorine contents were 59.9%-61.9% and 48.7%-52.8%. The concentrations of SCCPs and MCCPs were different in the soil collected in different sampling site. The concentration of SCCPs and MCCPs were relatively higher in soil of sewage treatment area and coating area. The CP levels in soil from the paper mill plant were at a high level compared with those in other regions. C10Cl6-7 and C14-15Cl5 were the main congener groups in most soil samples. The results of principal component analysis showed that the CP52 commercial products may be sources of SCCPs and MCCPs in the soil. The risk quotient (RQ) for SCCPs and MCCPs were assessed in soil of paper mill plant. The results showed that the RQ values for SCCPs in soil ranged from 0.01 to 0.73 which are the medium risk, and the RQ values for MCCPs in soil ranged from 0 to 0.07, which are the low risk. The human exposure values of children and adults are lower than TDI[10 μg·(kg·d)-1] in both cases. The health risks caused by non-dietary exposure under paper mill area are low.

Optimization of a low flow sampler for improved assessment of gas and particle bound exposure to chlorinated paraffins

An optimized low volume sampler was developed to determine both gas- and particle bound concentrations of short and medium-chain chlorinated paraffins (S/MCCPs). Background contamination was limited by the sampler design, providing method quantification limits (MQLs) at least two orders of magnitude lower than other studies within the gas (MQL: 500 pg (ΣSCCPs), 1.86 ng (ΣMCCPs)) and particle (MQL: 500 pg (ΣSCCPs), 1.72 ng (ΣMCCPs) phases. Good repeatability was observed between parallel indoor measurements (RSD ≤ 9.3% (gas), RSD ≤ 14% (particle)) with no breakthrough/saturation observed after a week of continuous sampling. For indoor air sampling, SCCPs were dominant within the gas phase (17 ± 4.9 ng/m3) compared to MCCPs (2.7 ± 0.8 ng/m3) while the opposite was observed in the particle bound fraction (0.28 ± 0.11 ng/m3 (ΣSCCPs) vs. 2.7 ± 1.0 ng/m3 (ΣMCCPs)). Only SCCPs in the gas phase could be detected reliably during outdoor sampling and were considerably lower compared to indoor concentrations (0.27 ± 0.10 ng/m3). Separation of the gas and particle bound phase was found to be crucial in applying the appropriate response factors for quantification based on the deconvoluted S/MCCP sample profile, thus avoiding over- (gas phase) or underestimation (particle phase) of reported concentrations. Very short chain chlorinated paraffins (vSCCPs, C5-C9) were also detected at equal or higher abundance compared to SCCP congener groups (C10-C13) congener groups, indicating an additional human indoor inhalation risk.

Chlorinated paraffins (SCCPs and MCCPs) in corals and water-SPM-sediment system in the Persian Gulf, Iran: A potential global threat for coral reefs

Swift degradation of the coral reef ecosystems urges the need to identify the reef decline drivers. Due to their widespread use, bioaccumulative and toxic characteristics, chlorinated organic compounds, such as chlorinated paraffins (CPs), are regarded as specific pollutants of concern. Yet little is known about the occurrence of CPs in the coral reef ecosystems. This study focuses on the short-chain chlorinated paraffins (SCCPs) and medium-chain chlorinated paraffins (MCCPs). Their distribution and congener pattern were investigated in the water-SPM-sediment system and in the corals of the Larak coral reef for the first time. Chlorinated paraffins were detected in all the coral species. Their total loadings ranged from 42.1 to 178ngg-1 dw in coral tissue, from 6.0 to 144ng g-1dw in the skeleton, and from 55.0 to 240ngg-1dw in zooxanthellae. Soft corals were found to accumulate more CPs than Scleractinian corals. Zooxanthellae and mucus accumulated more CPs than tissue and skeleton. In most cases, congener group patterns were dominated by C13 (for SCCPs) and C17 (MCCPs) groups, respectively. The congener patterns of CPs altered to some extent between mucus and the remaining coral compartments. High loadings of CPs were detected in the skeleton of the bleached corals. Moreover, a significant negative correlation between the levels of CPs and the symbiodinium density was observed.

Resolving mass fractions and congener group patterns of C8−C17 chlorinated paraffins in commercial products: Associations with source characterization

Commercial chlorinated paraffins (CPs) are a source of CPs in the environment, and clarification of the different CP groups present in commercial products is important for source characterization. Resolving CP congener groups is hindered by the complex CP compositions of commercial products. We used comprehensive two-dimensional gas chromatography coupled with electron capture negative ionization high-resolution time-of-flight mass spectrometry to profile 57 C8 − C17 CP congener groups in 18 CP-42, CP-52, and CP-70 commercial products. Very short-chain CPs (vSCCPs), including C8Cl5–8 and C9Cl5–9 CPs, and other chlorinated aromatic compounds were identified in the commercial products. The mass fractions of total vSCCPs, short-chain CPs (SCCPs) and medium-chain CPs (MCCPs) in the commercial products ranged from 0.02% to 3.61%, 0.75% to 51.4%, and 0.39% to 69.1%, respectively. Two-dimensional hierarchical cluster analysis with a heat map plot highlighted variations in the C8 − C17 CP congener group patterns among different commercial CP formulations. The principal component analysis results indicated that commercial CPs products might be important contributors to vSCCPs, SCCPs, and MCCPs in various environmental matrices. This study provides comprehensive and well-resolved compositional data for CPs in commercial products, which will be helpful for CP source characterization.

Refinement and extension of COSMO-RS-trained fragment contribution models for predicting the partition properties of C10-20 chlorinated paraffin congeners.

COSMO-RS-trained fragment contribution models (FCMs) to predict the partition properties of chlorinated paraffin (CP) congeners were refined and extended. The improvement includes (i) the use of an improved conformer generation method for COSMO-RS, (ii) extension of training and validation sets for FCMs up to C20 congeners covering short-chain (SCCPs), medium-chain (MCCPs) and long-chain CPs (LCCPs), and (iii) more realistic simulation of industrial CP mixture compositions by using a stochastic algorithm. Extension of the training set markedly improved the accuracy of model predictions for MCCPs and LCCPs, as compared to the previous study. The predicted values of the log octanol/water partition coefficients (Kow) for CP mixtures agreed well with experimentally determined values from the literature. Using the established FCMs, this study provided a set of quantum chemically based predictions for 193 congener groups (C10-20 and Cl0-21) regarding Kow, air/water (Kaw), and octanol/air (Koa) partition coefficients, subcooled liquid vapor pressure (VP) and aqueous solubility (Sw) in a temperature range of 5-45 °C as well as the respective enthalpy and internal energy changes.

Spatial distributions, source apportionment and ecological risks of C9-C17 chlorinated paraffins in mangrove sediments from Dongzhai Harbor, Hainan Island.

The spatial distributions, possible sources of C9-C17 chlorinated paraffins (CPs), and the ecological risks posed in mangrove sediment in Dongzhai Harbor (Hainan Island, China) were investigated. Comprehensive two-dimensional gas chromatography combined with electron capture negative ionization mass spectrometry was used to determine 50 C9-C17 CP congener groups. The concentrations of C9-CPs, short-chain CPs (SCCPs), and medium-chain CPs (MCCPs) in the mangrove sediment samples were 8.28-79.7, 89.2-931, and 58.8-834ngg-1 dry weight, respectively. The CPs concentrations in the mangrove sediment samples were moderate compared with those found in other regions worldwide. The spatial distributions and congener patterns of the CPs indicated that the CP concentrations were mainly controlled by local emissions and that wastewater discharged from livestock and shrimp breeding facilities and domestic sewage were the main sources of CPs in mangrove sediment in Dongzhai Harbor. C10Cl6-7 and C14Cl7-8 were the dominant SCCP and MCCP congener groups, respectively. The MCCP concentrations and total organic carbon contents significantly correlated (R2=0.607, P<0.05). Hierarchical cluster analysis and principal component analysis indicated that the SCCP and MCCP congeners were from different commercial CP formulations and sources. Risk assessments suggested that SCCPs and MCCPs in mangrove sediment in Dongzhai Harbor do not currently pose marked risks to sediment-dwelling organisms.

New data on Garra makiensis (Cyprinidae, Labeoinae) from the Awash River (Ethiopia) with remarks on its relationships to congeners on the Arabian Peninsula

On the African continent, the genus Garra consists of several species often insufficiently separated from each other by diagnostic characters. Herein, a detailed morphological redescription of Garra makiensis from the Awash River drainage is presented, together with additional data on the type specimens of G. makiensis and G. rothschildi. Mitochondrial CO1 sequence data are also provided, including the historic paralectotype of G. makiensis, with a comparison to Garra species from Africa and the Middle East. Based on these sequences, G. makiensis clusters outside the group of African congeners and is a sister lineage to species from the south-east of the Arabian Peninsula. Although morphologically variable, G. makiensis is characterised by having a single unbranched pectoral-fin ray, a short distance between vent and anal-fin origin (7.3–19.7 % of pelvic – anal distance), chest and belly covered with scales, and a prominent axillary scale at base of pelvic fin (18.8–35.5 % of pelvic-fin length).

A simplified screening method for short- and medium-chain chlorinated paraffins in food by gas chromatography-low resolution mass spectrometry

This study evaluates the performance of a simplified screening method for short- and medium-chain chlorinated paraffins (SCCPs and MCCPs, respectively) based on gas chromatography-electron capture negative ionization/mass spectrometry (GC-ECNI/MS) analysis and chlorine content quantification. The response from different combinations of ‘indicator’ congener groups present in technical mixture standards were used within calibration calculations to test the hypothesis that ∑SCCPs and ∑MCCPs could be quantified with acceptable accuracy using only a subset of the commonly analysed C10 to C17 and Cl5 to Cl10 groups. Potential combinations were assessed with respect to calibration curve performance and accuracy of SCCP and MCCP analysis of spiked food samples (olive oil, salmon, pork sausage, breakfast cereal, cow's milk and lard). Based on these trials, a screening method which quantifies ∑SCCPs and ∑MCCPs using only congener groups with 6 and 8 chlorine atoms for each carbon chain length was proposed. Concentrations of SCCPs and MCCPs in triplicate analyses of spiked food samples calculated using the proposed screening method deviated by ≤ 25% for the vast majority of samples (maximum deviation 37%) from levels determined using all analysed congener groups. The mean trueness of the screening method as applied to each of the spiked food samples and lard samples from a previous European Union Reference Laboratory (EURL) interlaboratory study ranged from 65 to 110% for ∑SCCPs and 102 to 175% for ∑MCCPs. Relative standard deviations (RSDs) were ≤ 25% for all triplicate analyses and matrix specific LOQs ranged from 0.7 to 6 ng/g ww for ∑SCCPs and from 1.3 to 12 ng/g ww for ∑MCCPs. The proposed screening method has the potential to deliver substantial time savings in instrumental analysis and manual labour without greatly reducing the overall accuracy and sensitivity of SCCP and MCCP quantification.