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Per- and polyfluoroalkyl acids (PFAAs) including polyfluoroalkyl carboxylic acids and polyfluoroalkyl sulfonic acids are a large category of crucial environmental pollutants of global concern. Besides known PFAAs, numerous unknown species may exist in the environment, urgently needing discovery and characterization. This study implemented nontarget analysis for a group of novel PFAA pollutants, viz., iodinated PFAAs (I-PFAAs) in wastewater from a fluorochemical manufacturing park by liquid chromatography-high-resolution mass spectrometry in combination with an iodine-specific data-processing algorithm. The algorithm took into account the diagnostic fragment iodine ion (I

Per- and polyfluoroalkyl acids (PFAAs) including polyfluoroalkyl carboxylic acids and polyfluoroalkyl sulfonic acids are a large category of crucial environmental pollutants of global concern. Besides known PFAAs, numerous unknown species may exist in the environment, urgently needing discovery and characterization. This study implemented nontarget analysis for a group of novel PFAA pollutants, viz. iodinated PFAAs (I-PFAAs) in wastewater by liquid chromatography-high-resolution mass spectrometry in combination with an iodine-specific data-processing algorithm. The algorithm took into account of the diagnostic fragment iodine ion (I–) together with carbon and sulfur isotopologue distributions. In total, 21 I-PFAA formulas involving 24 congeners were identified. Semiquantification was conducted, and the total concentrations of I-PFAAs were 1.9-311.9 ng/mL, indicating non-negligible pollution of I-PFAAs in the wastewater. The determined concentrations along with predicted environmental behaviors and toxicities demonstrate that I-PFAAs merit further in-depth investigation. The analytical method including the instrumental analysis and data-processing algorithm can be extended to screening and identification of I-PFAAs in other matrices. Furthermore, the analysis results for the first time provide cognition on the occurrence features and pollution status of I-PFAAs in the environment.

Distributions of chlorine isotopologues are potentially a fingerprint feature of organochlorines. However, the exact distributions remain little known. This study measured compound-specific chlorine isotopologue distributions of six polychlorinated organic compounds (POCs) for source identification. Complete chlorine isotopologues of POCs were detected by gas chromatography coupled to high-resolution mass spectrometry. The measured relative abundances (Ameas), theoretical relative abundances (Atheo), and relative variations between Ameas and Atheo (ΔA) of chlorine isotopologues were determined. These ΔA values were applied to characterize differences in isotopologue distribution patterns, and the ΔA patterns directly illustrated the distribution characteristics. Perchloroethylene (PCE) and trichloroethylene (TCE) from two manufacturers were chosen as model analytes to develop and validate the analytical method, including precision, concentration dependency, and temporal drift. The ΔA values of isotopologues of the PCE and TCE chemicals were from -82.5 to 19.9‰ with standard deviations (SDs) of 0.3-16.9‰. In addition, the ΔA values of the first three isotopologues (with 0-2 37Cl atoms) were from -15.5 to 19.9‰ with SDs of 0.3-1.6‰, showing sufficient precisions. No concentration dependency and temporal drift of ΔA were observed. The method has been successfully applied to source identification for PCE and TCE in commercial chemicals and plastic materials, and four polychlorinated biphenyls in chemicals and sediments, demonstrating that the ΔA values and ΔA patterns were discernable for POCs from different sources. This study demonstrates that compound-specific chlorine isotopologue distributions of POCs are differentiable and measurable, proposing a novel approach to perform fingerprinting analysis for the distributions, which is anticipated to facilitate source identification for organochlorine pollutants.

A reliable and sensitive analyzing method was developed and validated for determination of 13 novel bisphenol analogues (BPs) along with bisphenol A (BPA) in organism tissues. The complex organism tissues were treated by ultrasonic-assisted extraction using acetonitrile/formic acid (99:1, v/v), followed by successive purification using enhanced matrix removal-lipid sorbents and primary secondary amine sorbents. The BPs were finally determined by ultra-high performance liquid chromatography-tandem mass spectrometry after derivatization using pyridine-3-sulfonyl chloride. Satisfactory recoveries of 75 - 118% were obtained for the BPs, with good repeatability (RSD20%). Matrix interferences were efficiently diminished. The method quantification limits (MQLs) reached 0.003 - 0.1 ng g

Defect engineering in an electrocatalyst, such as doping, has the potential to significantly enhance its catalytic activity and stability. Herein, we report the use of a defect engineering strategy to enhance the electrochemical reactivity of Ti4O7 through Ce3+ doping (1-3 at. %), resulting in the significantly accelerated interfacial charge transfer and yielding a 37-129% increase in the anodic production of the hydroxyl radical (OH•). The Ce3+-doped Ti4O7 electrodes, [(Ti1-xCex)4O7], also exhibited a more stable electrocatalytic activity than the pristine Ti4O7 electrode so as to facilitate the long-term operation. Furthermore, (Ti1-xCex)4O7 electrodes were also shown to effectively mineralize perfluorooctanesulfonate (PFOS) in electrooxidation processes in both a trace-concentration river water sample and a simulated preconcentration waste stream sample. A 3 at. % dopant amount of Ce3+ resulted in a PFOS oxidation rate 2.4× greater than that of the pristine Ti4O7 electrode. X-ray photoelectron spectroscopy results suggest that Ce3+ doping created surficial oxygen vacancies that may be responsible for the enhanced electrochemical reactivity and stability of the (Ti1-xCex)4O7 electrodes. Results of this study provide insights into the defect engineering strategy for boosting the electrochemical performance of the Ti4O7 electrode with a robust reactivity and stability.

H-Abstraction reactions occurring during electron impact ionization processes in electron ionization mass spectrometry (EI-MS) are a long-standing and crucial topic in MS research. Yet, some critical relevant mechanisms are controversial and ambiguous, and information about the EI-induced H-abstraction reactions of halogenated organic compounds (HOCs) is completely in the dark. This study provides a systematic investigation of H-abstraction reactions of HOCs taking place in the EI source using 13C6-hexachlorobenzene (13C6-HCB) and 13C6-hexabromobenzene (13C6-HBB) as exemplary compounds by gas chromatography (GC)–high-resolution mass spectrometry (GC–HRMS). The H-abstraction efficiencies were evaluated with the MS signal intensity ratios of ions with H-abstraction relative to the corresponding original ions (without H-abstraction). Ion source temperatures, EI energies, and numbers of heavy isotope atoms (37Cl or 81Br) of isotopologues were investigated in terms of their effects on the H-abstraction efficiencies. The H-abstraction efficiencies of individual isotopologues generally decreased from the first to the last isotopologues of respective ions, and those of individual ions were different from each other, with the highest values of 0.017 and 0.444 for 13C6-HCB and 13C6-HBB, respectively. The overall H-abstraction efficiencies involving all measured ions of 13C6-HCB and 13C6-HBB were 0.004 and 0.128, respectively. With increasing ion source temperatures, the H-abstraction efficiencies first increased to a summit and then began to linearly decrease. EI energies and emission currents could impact the H-abstraction efficiencies but showed no certain tendency. The H-abstraction reactions were inferred to belong to ion–molecule reactions, and the siloxanes bleeding from the GC column might be a hydrogen source. Some strategies were proposed for eliminating or alleviating the interference triggered by the H-abstraction reactions in EI-MS in identification of halogenated organic pollutants (HOPs). Our findings provide a better understanding of the EI-induced H-abstraction reactions of HOCs and may benefit the identification of HOPs in environmental analysis, especially for novel HOPs.

Relative abundances of chlorine and carbon isotopologues of individual organochlorines (e.g. polychlorinated organic pollutants) are generally recognised to comply with stochastic distribution, and thus can be calculated by the binomial theorem. As a result, carbon isotope ratios derived from different chlorine-isotopologue pairs, e.g. 12C235Cl4 vs. 12C13C35Cl4, should be consistent. Yet this recognition may not exactly reflect the reality. This study investigated the consistency/inconsistency of carbon isotope compositions of chlorine-isotopologue pairs of individual organochlorines including two chloroethylenes, three polychlorinated biphenyls, methyl-triclosan and hexachlorobenzene. The raw carbon isotope ratios were measured by gas chromatography-high resolution mass spectrometry. Data simulations in terms of background subtraction, background addition, dual 13C-atoms substitution, deuterium substitution and hydrogen-transfer, along with measurements at different injection concentrations were conducted to confirm the validity of measured carbon isotope ratios and their differences. Inconsistent carbon isotope ratios derived from chlorine-isotopologue pairs of individual organochlorines were observed, and the isotopologues of each organochlorine were thus inferred to be non-randomly distributed. Mechanistic interpretation for these findings was tentatively proposed according to a basic principle in clumped-isotope geochemistry, reaction thermodynamics and kinetics, along with isotope effects occurring in electron ionisation mass spectrometry. This study sheds light on the actual carbon isotope compositions of chlorine-isotopologue pairs of organochlorines, and yields new insights into the real distributions of carbon and chlorine isotopologues. The inconsistent carbon isotope compositions of chlorine-isotopologue pairs are anticipated to benefit the exploration of formation conditions and source identification of organochlorine pollutants.

Revelation of chlorine and bromine isotope effects in fragmentation is crucial for compound-specific isotope analysis of chlorine/bromine (CSIA-Cl/Br) using gas chromatography-electron ionization mass spectrometry (GC-EI-MS), but theoretical fundamentals of the isotope effects remain unclear. Herein, this study provides a theoretical basis for elucidating the details and implications of chlorine and bromine isotope effects occurring in dehalogenation reactions in EI-MS. Inter-ion and intra-ion isotope effects can occur in dehalogenation reactions in EI-MS, and affect chlorine/bromine isotope ratios. In a dehalogenation reaction, inter-ion isotope effects increase the isotope ratio of a precursor ion but decrease that of its product ion. On the other hand, intra-ion isotope effects can only affect (increase) the isotope ratio of a product ion, and have no effect on its precursor ion. The chlorine/bromine isotopologue distributions of ions measured by EI-MS are deduced to be non-binomial (nonrandom), regardless of the initial isotopologue distributions prior to fragmentation. The bulk chlorine/bromine isotope ratio of an ion cannot be exactly achieved with a calculation scheme using an arbitrary pair or pairs of neighboring chlorine/bromine isotopologues, but can be calculated with complete isotopologues of the ion. The isotope ratio of a compound calculated with a pair/pairs of neighboring isotopologues could not accurately reflect the trueness, even though it has been calibrated with external isotopic standard(s), due to different isotopologue distributions of the analyte and external isotopic standard(s). The conclusions derived from theoretical derivation have been experimentally proven with the isotopically distinct standards of tetrachloroethylene and trichloroethylene from different manufacturers. The findings of this study are conducive to CSIA-Cl/Br using GC-EI-MS to obtain high-quality data, and provide new insights into the actual chlorine/bromine isotopologue distributions of chlorinated/brominated organic compounds.

Tissue distributions and body-size dependent and species-specific bioaccumulation of 12 organic ultraviolet absorbents (UVAs) were investigated in 9 species of wildlife freshwater fish from the Pearl River catchment, South China. The concentrations of the 12 UVAs were from 109 to 2320 ng/g lipid weight in the fish tissue samples. The UVAs 2-hydroxy-4-methoxybenzophenone (BP-3), octocrylene (OCR), UV531, and 5 benzotriazole UV stabilizers (UVP, UV329, UV234, UV328, and UV327) were detected in more than half of the fish tissue samples. The UVA UV531 showed an obvious potential for bioaccumulation in the wild freshwater fish, with an estimated bioaccumulation factor (log BAF) and a biota-sediment accumulation factor (BSAF) of 4.54 ± 0.55 and 4.88 ± 6.78, respectively. Generally, liver (989 ± 464 ng/g lipid wt) contained the highest level of UVAs, followed in decreasing order by belly fat (599 ± 318 ng/g lipid wt), swimming bladder (494 ± 282 ng/g lipid wt), dorsal muscle (470 ± 240 ng/g lipid wt), and egg (442 ± 238 ng/g lipid wt). The bioaccumulation of UVAs in the freshwater wild fish was species specific and compound dependent. Bottom-dwelling detritus-ingesting omnivorous fish contained obviously higher UVA concentrations, suggesting that detritus/sediment ingestion is a significant pathway for exposure of the wild freshwater fish to the UVAs. The UVAs UV531 and BP-3 demonstrated a potential for growth dilution. Metabolism might play a significant role in elimination of the UVAs in the fish tissues, with the highest rate of metabolism in the liver. The UVAs did not demonstrate obvious trophic magnification in the freshwater ecosystem of the Pearl River catchment. More research is warranted to elucidate maternal transfer of the UVAs. Environ Toxicol Chem 2020;39:343-351. © 2019 SETAC.

Halogenated organic compounds (HOCs) are a huge group of pollutants, which have caused severe environmental pollution worldwide. This study developed a nontarget analysis method for characterization of known and unknown HOCs in tap water, fly ash, soil and sediment using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) with aid of scripting data-processing approaches. The FT-ICR-MS was equipped with an electrospray ionization source operated in negative ion mode, and full scan at a mass resolution around 200,000 was applied. Data screening scripts were developed based on exact mass differences and abundance ratios between neighboring chlorine/bromine isotopologues. Cosine similarity analysis was applied to evaluating similarity between measured and simulated isotopologue distributions which were constituted by abundance ratios between neighboring isotopologues for identification of polychlorinated and polybrominated compounds. From huge amount of peaks in raw mass spectra, thousands of MS features of HOCs were screened out. In total 824 HOC formulae were finally identified, including 702 organochlorines, 108 organobromines, and 14 mix-chlorine/bromine-containing organic compounds (OClBrs), mainly being monochlorinated/monobrominated compounds (∼90%) whose abundances were also the most prominent. Dozens of HOCs were tentatively structurally elucidated, including halogenated phenols, carboxylic acids, benzenesulfonic acids, etc. Three novel OClBrs were structurally identified, i.e., bromochlorobenzoic acid, bromodichlorophenol and bromotrichlorophenol. The data-processing scripts and strategies can facilitate accurate and high-throughput nontarget analysis of both common and novel/emerging halogenated organic pollutants in complex matrices. The research results provide informative insights into pollution profiles of HOCs in the environment, suggesting that halogenated organic pollutants remain to be seriously concerned.

Alkylamides are used as plastic additives in various materials and products, potentially posing risks to human health and the environment. Besides reported alkylamides in plastics, many unknown alkylamides may exist in various plastics, which are needing identification and characterization. This study performed nontarget analysis of alkylamides in electrical product plastics by gas chromatography-positive chemical ionization high-resolution mass spectrometry in full scan mode and an in-house developed data-processing algorithm. The algorithm was based on exact mass discrepancies and signal intensities of specific fragment and adduct ions of alkylamides, and was able to efficiently screen and anchor quasi-molecular ions. As a whole, 36 alkylamides were identified, of which 7 were found in all the plastics and 14 were observed in ≥ 2 plastics. The content distributions were elucidated with normalized abundances of quasi-molecular ions of alkylamides. Oleamide showed chromatographic peaks with the highest abundances in individual samples and was the most abundant alkylamide in all the plastics, of which the normalized abundances accounted for 57.42-70.06% of the total abundances of all alkylamides. Besides, (2E)-2-hexenamide, palmitamide and stearamide showed relatively high abundances, of which the relative abundances were 6.99-25.79%. The high abundances together with predicted environmental behaviors and toxicities indicate that alkylamides in plastics are worthy of further in-depth research. The nontarget analysis method including the instrumental analysis and data-processing algorithm can be applied to identification and characterization of alkylamides in more diverse matrices. In addition, the analysis results for the first time provide knowledge about the specific characteristics and relative content distributions of alkylamides in electrical product plastics from a comprehensive perspective.

Nontarget analysis enables high-efficiency screening and identification of halogenated organic pollutants (HOPs) in complex matrices irrespective of lacking authentic standards, particularly for novel and emerging species, thereby realizing comprehensive component characterization of HOPs. Notwithstanding, nontarget analysis and comprehensive characterization of HOPs remain on the way to improvement. In this study, we implemented nontarget analysis of HOPs in fly ash, egg and sediment using gas chromatography quadrupole-orbitrap high-resolution mass spectrometry with the aid of chromatogram segmentation and Cl/Br-specific screening algorithms, and further performed comprehensive characterization of components and distribution of HOPs. In total, 122 HOP formulas were identified and tentatively assigned with structures, of which 28 were found in ≥ two matrices. Taking isomers into account, in total 1059 HOP congeners were found. Based on the identification and semiquantification results, the chemical components and concentration profiles of HOPs were preliminarily clarified, and accordingly the overall pollution signatures of HOPs were sketched. The total concentrations of HOPs in the fly ash, egg and sediment were 4.7, 41.2 and 750.8 μg g

Relative abundances of chlorine isotopologues of polychlorinated organic compounds (POCs) are commonly recognized to comply with binomial distribution. This study investigated whether chlorine isotopologue distributions of polychlorinated organic pollutants are binomial and evaluated implications of the distributions to relevant analytical and environmental research by theoretical derivation, numerical simulation and experiment. Chlorine kinetic isotope effects and equilibrium isotope effects vary in stepwise chlorination reactions, leading to inconsistent chlorine isotope ratios on different reaction positions of products, which results in non-binomial chlorine isotopologue distributions of the products. After physical changes and dechlorination, chlorine isotopologues of POCs are unlikely binomially distributed. The experimental results demonstrated that the chlorine isotopologue distributions of perchloroethylene, trichloroethylene, methyl-triclosan, and 2,3,7,8-tetrachlorodibenzofuran in standards and four polychlorinated biphenyls in both standard solutions and sediments were non-binomial. The patterns of chlorine isotope ratios derived from pairs of neighboring chlorine isotopologues of POCs from different sources were different, implying different isotopologue distributions, which might cause biases in compound-specific isotope analysis of chlorine (CSIA-Cl) and source identification. A complete-isotopologue scheme for isotope ratio calculation is recommended to CSIA-Cl for obtaining accurate data. Gas chromatography-double focusing magnetic-sector high resolution mass spectrometry is a promising instrument for CSIA-Cl that uses the complete-isotopologue scheme due to its excellent sensitivity, selectivity and ruggedness. This study yields new insights into chlorine isotopologue distributions of polychlorinated organic pollutants and proposes practicable solutions to improve CSIA-Cl that uses gas chromatography-mass spectrometry and facilitate source identification of polychlorinated organic pollutants.

Defect engineering in an electrocatalyst, such as doping, has the potential to significantly enhance its catalytic activity and stability. Herein, we report the use of a defect engineering strategy to enhance the electrochemical reactivity of Ti

With the development of technology, FTP protocol has been widely used but also brought many threats and hidden dangers, including remote attacks, denial of service and so on. Aiming at the above problems, this study develops a vulnerability mining and evaluation technique for FTP protocol based on Fuzzing. This project use Python programming to implement Fuzzing. Using freefloatftp software to build a simple FTP server in Windows XP SP3 operating system. Ftpfuzzer.py is used to attack the server. Besides, Immunity Debugger is used to preliminarily analyze the vulnerabilities mined, so as to provide direction for resisting attacks.

Parabens, bisphenol A (BPA), triclosan, and triclocarban are recognized endocrine-disrupting contaminants (EDCs); and their occurrence in the environment has attracted increasing concern. Body size-dependent bioaccumulation, tissue distribution, trophic magnification, and maternal transfer of methyl-, ethyl-, propyl-, and butylparabens; 2-phenylphenol (PHP); BPA; triclosan; and triclocarban were investigated in freshwater fish of the Pearl River catchment, China. Most of the EDCs were detected in more than half of the biota samples, ranging from not detected to 6750 ng g-1 lipid weight, with median concentrations of 5 to 72 ng g-1 lipid weight. Livers generally contained the highest EDC levels (1609 ± 1860 ng g-1 lipid wt, mean ± standard deviation), followed in decreasing order by eggs (842 ± 1317 ng g-1 lipid wt), belly fats (488 ± 465 ng g-1 lipid wt), and dorsal muscles (240 ± 239 ng g-1 lipid wt) of the wildlife. Body size-dependent bioaccumulation of the EDCs was observed in the freshwater fish, which varied according to species, tissue, and compound. The concentrations of triclosan, PHP, and BPA usually showed decreasing trends, whereas parabens mostly demonstrated increasing tendency with increasing fish weights, indicating effects of growth dilution and bioaccumulation, respectively. Potential biomagnification was shown by triclosan with trophic magnification factors of 3.0, 4.3, and 4.0 in liver, belly fat, and dorsal muscle, respectively. In addition, the potential of maternal transfer in the fish was primarily revealed for methyl- and propylparabens, PHP, triclosan, and BPA. Presence of the EDCs in the freshwater organisms of the Pearl River catchment warrants more attention considering the potential of trophic magnification and maternal transfer. Environ Toxicol Chem 2018;37:1811-1823. © 2018 SETAC.

Compound-specific isotope analysis of chlorine (CSIA-Cl) is a practicable and high-performance approach for revelation of transformation processes and source identification of chlorinated organic pollutants. This study conducted CSIA-Cl for typical polychlorinated organic pollutants using gas chromatography-high resolution mass spectrometry (GC HRMS) with an alternate injection mode using perchloroethylene (PCE) and trichloroethylene (TCE) as model analytes. PCE and TCE standards from two manufacturers were employed for method development, and chlorine isotope ratio calculation schemes were evaluated by experiment and numerical simulation. The achieved precision (standard deviation of isotope ratios) was up to 0.21‰ for PCE and 0.43‰ for TCE. The limits of detection for CSIA-Cl of were 0.05 μg/mL (0.05 ng on column), and the linearities were 0.05–1 μg/mL. Two isotope ratio calculation schemes, i.e., one using complete molecular isotopologues and another using the first pair of neighboring chlorine isotopologues of each analyte, were evaluated in terms of accuracy and precision. The complete-isotopologue scheme showed evidently higher precision and was more competent to reflect trueness than the isotopologue-pair scheme and the two schemes could present completely different outcomes. The method has been successfully applied to PCE and TCE reagents from different suppliers, a trichloromethane reagent, and a plastic material. The relative isotope ratio variations (Δ37Cl) of PCE and TCE in the reagents and plastic material were from −1.84±0.7‰ to 15.12±0.85‰. The analytes from different sources could mostly be discerned from each other by chlorine isotope ratios. This study will be conducive to transformation process elucidation and source identification of for PCE and TCE, and facilitate CSIA-Cl using GC–MS for more polychlorinated organic pollutants, particularly in selection and optimization of isotope ratio calculation schemes.

Chlorophenols are a category of toxic pollutants that are ubiquitously present in the environment. This paper presents a reliable and feasible method for the determination of five chlorophenols in ...

Polybrominated dibenzo-p-dioxins (PBDDs) and hydroxylated polybrominated diphenyl ethers (OH-PBDEs) can be formed from bromophenols (BPs) by thermal degradation, biosynthesis or phototransformation. However, it is unknown whether PBDDs and OH-PBDEs can be formed during the chemical production processes that utilize BPs as raw materials. 2,4,6-tribromophenol (2,4,6-TBP) is an important raw material for the synthesis of 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), a novel brominated flame retardant. In this study, PBDDs, polybrominated dibenzofurans (PBDFs) and OH-PBDEs have been identified and quantified in commercially available BTBPE and 2,4,6-TBP. Furthermore, their formation as unintentional by-products during the laboratory synthesis of BTBPE from 2,4,6-TBP and 1,2-dibromoethane in the presence of sodium carbonate has also been investigated. 2,3,7,8-substituted PBDDs and PBDFs (2,3,7,8-PBDD/Fs) were undetectable in commercial samples of BTBPE and present in low levels (nanogram per gram) in 2,4,6-TBP. Two tetrabrominated dibenzo-p-dioxins (TeBDDs), namely 1,3,6,8- and 1,3,7,9-TeBDD, and three hydroxylated pentabrominated diphenyl ethers (OH-pentaBDEs), namely 4'-OH-BDE121, 2'-OH-BDE121, and 6'-OH-BDE100, were identified or tentatively identified, and quantitatively estimated to be at concentrations in the range of undetectable to several thousands of nanograms per gram in commercial BTBPE and 2,4,6-TBP. TeBDDs and OH-pentaBDEs were formed as by-products from 2,4,6-TBP during BTBPE synthesis. Further studies need to be conducted in order to determine whether PBDD/Fs and OH-PBDEs are also formed during the industrial synthesis of other chemical compounds that utilize BPs as raw materials or intermediates.

A variety of personal care products have been classified as emerging contaminants (ECs). Occurrence, fate, spatial and vertical profiles of 13 ultraviolet absorbents, triclocarban (TCC) and its dechlorinated products, triclosan (TCS), 2-phenylphenol and parabens were investigated in riverine and estuarine sediment of the Pearl River catchment, China. Bisphenol A (BPA), a widely applied plasticizer, was also investigated. The ECs were widely present in the bed sediment. TCC was the most abundant with a maximum concentration of 332ngg-1 dry weight. The other prominent ECs included BPA, TCS, octocrylene, and benzotriazole UV stabilizers UV326 and UV328. Treated wastewater effluent was the major source of the ECs in the riverine sediment. TCC, BPA, TCS, methyparaben, UV531, UV326, and UV328 were also detected throughout the estuarine sediment cores, indicating their persistence in the sediment. Temporal trends of the ECs in the sediment cores reflected a combined effect of industrial development, population growth, human life quality improvement, and waste treatment capacity in the Pearl River Delta over the last decades. TCC dechlorination products were frequently detected in the bed sediment with higher levels near treated effluent outlets but only occasionally observed in the sediment cores, suggesting insignificant in-situ TCC dechlorination in the sediment.

It has been reported that isotope fractionation can occur on gas chromatography (GC), yet little is known about concurrent dual-elements isotope fractionations on GC. Revelation of concurrent two-dimensional carbon and chlorine/bromine isotope fractionations of halogenated organic compounds (HOCs) on GC may be of important significance for compound-specific isotope analysis (CSIA). This study presents an in-depth investigation of the two-dimensional C and Cl/Br isotope fractionations of HOCs on GC using GC-double focus magnetic-sector high resolution mass spectrometry (GC-DFS-HRMS). The two-dimensional C and Cl/Br isotope fractionations of four organochlorines and four bromobenzenes on GC were simultaneously measured by GC-DFS-HRMS. The isotope fractionations were evaluated with isotope ratios, relative variations of isotope ratios and isotope fractionation extents. All the HOCs exhibited significant inverse C and Cl/Br isotope fractionations. The isotope fractionations were significant in both ends of chromatographic peaks, while the isotope ratios in center retention-time segments were the closest to comprehensive isotope ratios in the whole peaks. Significant correlations between C isotope fractionation and Cl/Br isotope fractionation were observed, indicating that the isotope fractionations might have strong relationships and/or be dominated by similar factors. Relevant mechanisms for the two-dimensional C and Cl/Br isotope fractionations were tentatively proposed on basis of a modified two-film model and the theories related to zero point energy. The results of this study gains new insights into concurrent two-dimensional isotope fractionation behaviors of HOCs during physical processes, and are conducive to CSIA studies involving C, Cl and Br for obtaining high-quality data, particularly to dual-elements CSIA of C and Cl/Br., 45 pages, 6 figures

Hexa-mix-chlorinated/brominated benzenes (HXBs), a group of newly found analogues of hexachlorobenzene (HCB) and hexabromobenzene (HBB), may exhibit similar environmental risks and toxicities as HCB and HBB, and therefore possess high interests in environmental and toxicological research. Yet information regarding HXBs in the environment remains scarce. In this study, we developed an isotope dilution method for quantitative and semiquantitative determination of five HXBs in fly ash, soil and air using gas chromatography high resolution mass spectrometry (GC-HRMS) in multiple ion detection mode. The samples were Soxhlet-extracted and purified with multilayer composite silica gel-alumina columns, followed by GC-HRMS detection. Identification of HXBs was conducted by the comparison between theoretical and detected mass spectra using paired-samples T test and cosine similarity analysis. Two HXBs (C6BrCl5 and C6Br4Cl2) with reference standards were quantitatively determined while the rest three (C6Br2Cl4, C6Br3Cl3 and C6Br5Cl) without reference standards were semiquantitatively analyzed by sharing the calibration curves of C6BrCl5 and C6Br4Cl2 in cooperation with isotopologue distribution computation. The accuracies for C6BrCl5 and C6Br4Cl2 were 87.3–107.8% with relative standard deviations (RSD) of 2.8–5.0%. The method limits of quantification of the HXBs were 0.10 ng/g in fly ash and soil samples and 0.09 pg/m3 in ambient air samples. The recoveries ranged from 42.7% to 102.1% with RSD of 3.7–13.9%. This method has been successfully applied to the analysis of the HXBs in the environmental samples. The total concentrations of HXBs in the fly ash, soil and ambient air samples were 19.48 ng/g, 10.44 ng/g and 5.13 pg/m3, respectively, which accounted for 10.6%, 0.4% and 10.8% of the corresponding total concentrations of HCB and HBB. This study provides a reference method for quantitative and/or semiquantitative analyses of novel mix-halogenated organic compounds, and sheds light on the full picture of HXBs pollution in the environment.

Freshwater systems are an important source and vector of plastic debris found in oceans. However, plastic debris in freshwater organisms has not been well studied. The occurrence, characterization, polymer composition, and seasonal and spatial distribution of plastic debris were investigated in 9 species of wild freshwater fish from the Pearl River catchment, south China. Approximately 50% of the total fish (n = 279) belonging to 9 species were found to ingest plastic debris with an average abundance of 7.0 ± 23.8 items/individual, indicating wide plastic contamination in the Pearl River catchment. Plastic debris were predominantly transparent or white in color, fibers or fragments in shape, and polyethylene, polypropylene, ethylene-propylene copolymer (PE-PP), and polyethylene terephthalate (PET) in polymer composition. A species-specific distribution of the plastic debris was observed in terms of abundance, shape, and polymer composition. Redbelly tilapia had the highest (27.4 ± 54.0 items/individual), whereas common carp had the lowest (0.2 ± 0.4 items/individual) abundance of the plastic debris in their gastrointestinal tracts. Fibers of PET were predominant in the freshwater species except in barbel chubs, which had mostly PE-PP fragments. Omnivores and bottom-dwellers were more likely to ingest plastic debris. Seasonal variation was observed, with generally higher abundance of plastic debris in fish collected in the dry season than in the wet season. Environ Toxicol Chem 2019;38:1504-1513. © 2019 SETAC.

Revealing fractionations of chlorine and bromine isotope in electron ionization mass spectrometry (EI-MS) is crucial for accurate compound-specific isotope analysis of chlorine/bromine (CSIA-Cl/Br) for halogenated organic compounds (HOCs) using gas chromatography EI-MS (GC-EI-MS). This study investigated chlorine/bromine isotope fractionation of 12 organochlorines and 5 organobromines in EI-MS using gas chromatography-high resolution mass spectrometry. The observed isotope fractionations were evaluated with relative variation of chlorine/bromine isotope ratios (Δ37Cl or Δ81Br) between precursor ions and their product ions. All the 17 HOCs exhibited significant isotope fractionations with varied modes and magnitudes depending on compound and EI energy. The magnitudes of the observed isotope fractionations were extremely large in contrast to those in in-solution dehalogenation reactions, showing the Δ37Cl and Δ81Br values within the ranges of -149.2 to 292.0‰ and -362.2 to 546.2‰, respectively. Inter-ion and intra-ion isotope fractionations counteractively influenced the measured chlorine/bromine isotope ratios of individual dehalogenation product ions, whereas only the former could affect (enhance) the measured isotope ratios of molecular ions. The magnitudes of inter-ion isotope fractionation were generally lower than those of intra-ion isotope fractionation for most HOCs (11/17). Stable EI energy and isotope-ratio calculation using complete chlorine/bromine isotopologues of individual molecular ions help to obtain CSIA-Cl/Br data with high precision and accuracy. The results of this study could facilitate exploration of chlorine and bromine isotope fractionations of HOCs during dehalogenation in such conditions as photoinduced dehalogenation, and further elucidate relevant dehalogenation pathways in light of reaction mechanisms revealed by CSIA data.

Metabolite identification is crucial for revealing metabolic pathways and comprehensive potential toxicities of polycyclic aromatic hydrocarbons (PAHs) in human body. In this work, a quasi-targeted analysis strategy was proposed for metabolite identification of monohydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in human urine using liquid chromatography triple quadruple mass spectrometry (LC-QqQ-MS/MS) combined with liquid chromatography high resolution mass spectrometry (LC-HRMS). Potential metabolites of OH-PAHs were preliminarily screened out by LC-QqQ-MS/MS in association with filtering in a self-constructed information list of possible metabolites, followed by further identification and confirmation with LC-HRMS. The developed method can provide more reliable and systematic results compared with traditional untargeted analysis using LC-HRMS. In addition, data processing for LC-HRMS analysis were greatly simplified. This quasi-targeted analysis method was successfully applied to identifying phase I and phase II metabolites of OH-PAHs in human urine. Five metabolites of hydroxynaphthalene, seven of hydroxyfluorene, four of hydroxyphenanthrene, and three of hydroxypyrene were tentatively identified. Metabolic pathways of PAHs in human body were putatively revealed based on the identified metabolites. The experimental results will be valuable for investigating the metabolic processes of PAHs in human body, and the quasi-targeted analysis strategy can be expanded to the metabolite identification and profiling of other compounds in vivo.

Kinetic isotope effects (KIEs) occurring in mass spectrometry (MS) can provide in-depth insights into the fragmentation behaviors of compounds of interest in MS. Yet, the fundamentals of KIEs in collision-induced dissociation (CID) in tandem mass spectrometry (MS/MS) are unclear, and information about chlorine KIEs (Cl-KIEs) of organochlorines in MS is particularly scarce. This study investigated the Cl-KIEs of dichloromethane, trichloroethylene, and tetrachloroethylene during CID using gas chromatography-electron ionization triple-quadrupole MS/MS. Cl-KIEs were evaluated with MS signal intensities. All the organochlorines presented large inverse Cl-KIEs (

Dechlorination reactions of organochlorines can commonly take place in fragmentation on electron ionization mass spectrometry (EI-MS) and collision-induced dissociation (CID) on electron ionization tandem mass spectrometry (EI-MS/MS), possibly accompanied with chlorine isotope effects. However, it remains unclear whether characteristics of chlorine isotope effects of individual organochlorines occurring on different types of mass spectrometers are similar or different. Revelation of characteristics of chlorine isotope effects on different mass spectrometers may help to elucidate mechanisms of dechlorination reactions and fragmental pathways of organochlorines. This study investigated the characteristics of chlorine isotope effects of two model organochlorines, i.e., tetrachloroethylene and trichloroethylene, during fragmentation/CID on EI-double focusing magnetic-sector high resolution MS (EI-HRMS), EI-quadrupole MS (EI-qMS) and EI-triple-quadrupole MS/MS (EI-MS/MS) that were all coupled with gas chromatography (GC). The patterns of chlorine isotope ratios measured by different instruments were different, showing different characteristics of chlorine isotope effects. On EI-HRMS, both normal and inverse chlorine isotope effects were observed; while on EI-qMS, only normal isotope effects were found, and on EI-MS/MS merely inverse isotope effects were discovered. On EI-HRMS and EI-qMS, inter-ion and intra-ion chlorine kinetic isotope effects (Cl-KIEs) might participate in isotope fractionation processes and contribute to inverse inter-ion and normal intra-ion isotope effects, respectively, and the dominant isotope effects determined the direction of observed (apparent) isotope effects. On EI-MS/MS, both inter-ion and intra-ion Cl-KIEs were inverse at high collision energies (including 30 and 45 eV) and contributed to normal inter-ion and inverse intra-ion isotope effects, respectively, and the inverse intra-ion isotope effects were the dominant, leading to the inverse apparent isotope effects in all dechlorination reactions. Particularly, the chlorine isotope ratios measured by EI-qMS exponentially decreased with the increasing Cl atoms of ions, implying that the intra-ion isotope effects rose as broken C–Cl bonds increased. Moreover, fundamentals of chlorine isotope effects in the stepwise multibond dechlorination reactions were revealed with the aid of density functional theory calculations. The different measurement timescales and geometries of the mass spectrometers and the difference in EI-induced fragmentation and CID might result in the different characteristics of chlorine isotope effects. This study may be conducive to elucidating isotope fractionation behaviors and fragmental pathways of organochlorines on EI-MS(/MS), and provides new insights into the mechanisms of dechlorination reactions losing multiple chlorine atoms.

Identifying environmental pollutants, particularly emerging and new pollutants, in various matrices is a prerequisite for further research involving these pollutants. In this study, we developed a quasi-targeted analysis method to identify halogenated organic pollutants (HOPs) by joint application of gas chromatography-double focus magnetic-sector high resolution mass spectrometry (GC-DFS-HRMS), isotopologue distribution comparison and predicted retention time (PRT) alignment. Structures of a variety of unreported/scarcely reported HOPs were conceived and sketched, and then, multiple isotopologue ions of individual HOPs were detected by GC-DFS-HRMS in multiple ion detection mode. Comparisons between the detected mass spectra and the theoretically simulated isotopologue distributions were conducted via paired-samples T-test and cosine similarity analysis. PRT alignment was further applied to exclude interferences that presented unreasonable retention times. The method was validated with dozens of commercially available reference standards of conventional HOPs and several unintended byproducts comprising mix-chlorinated/brominated benzenes in some commercial halogenated-benzene standards, showing good reliability and accuracy. Application of the developed method was primarily implemented with fly ash from municipal solid waste incineration plants. In total, 106 molecular formulas corresponding to unknown or little-known HOPs were identified, of which many were mix-halogenated compounds. Six HOPs were structurally elucidated, including three sulfur-containing dioxin-like HOPs, two mix-perhalogenated benzenes, and a pentabrominated anisole. The structures of 18 compounds that individually contained 2-4 theoretical isomers were putatively elucidated according to the PRT alignment. In addition to fly ash, other environmental matrices, including soil, ambient air and flue gas, were screened by the method, and a number of HOPs were also found in these matrices. This method is feasible, reliable, accurate and sensitive for the identification and screening of potential unknown HOPs in the environment and should facilitate further research, such as pollution investigations and eco-environmental risk assessments for these pollutants.

Rationale: Ultra-high-performance liquid chromatography coupled with electrospray ionization mass spectrometry (UPLC/ESI-MS) has been frequently used for chemical analysis. A redox reaction in the ESI source has been observed during the ionization process. However, it is still unclear whether this redox reaction can take place on UPLC columns. Methods: In this study, the oxidation reactions potentially occurring on UPLC columns were investigated using polyphenols including baicalin, baicalein, propyl gallate (PG), quercetin-3-rhamnoside (QR), rutin, naringin and 2,3,5,4'-tetrahydroxystilbene-2-Ο-β-D-glucoside (THS-G) as model compounds. The on-column oxidation reaction was ascertained by post-column infusion of antioxidants such as ammonium sulfide ((NH4)2S). The oxidized products were reduced to their parent forms in the ESI source. This on-column oxidation reaction was further confirmed by means of post-column infusion of baicalin solution. Results: On-column oxidation reactions were observed and confirmed for baicalin, baicalein, PG, rutin, and QR. The exact reaction site was located at the outlet frits of the UPLC columns. (NH4)2S was proved to be the most suitable reducing agent among the tested antioxidants for eliminating negative effects caused by on-column oxidation reaction. It was subsequently proposed to be an efficient additive to suppress oxidation reactions in the ESI source. Conclusions: Oxidation reactions can take place at the outlet frits of UPLC columns. Ascertaining on-column oxidation reactions and consequently eliminating relevant negative effects are of great interest for determination of oxidation-sensitive compounds such as polyphenols. Copyright © 2015 John Wiley & Sons, Ltd.

This study aimed to assess the dietary intake of human essential elements of local residents in Shenzhen, Guangdong province, China, using a Total Diet Study (TDS). The levels of eight human essential elements, Na, K, Mg, Ca, Fe, Mn, Zn, and Cu, in a total of 243 food samples collected in January 2011, were determined. Na, Mg, K, and Ca were the major elements, and their concentrations were approximately 2–3 orders of magnitude higher than those of other metals, which are trace elements in the human body. For the eight elements, the total dietary metal intake of Shenzhen residents was 2840 (Na), 2110 (K), 173 (Mg), 391 (Ca), 7.28 (Fe), 2.09 (Mn), 7.47 (Zn), and 1.11 (Cu) mg/d. The dietary intake of Na exceeded the reference values, whereas the Ca intake was insufficient. The dietary intake of the other six elements conformed to the recommended doses. Because excess Na and insufficient Ca could cause adverse effects, a low sodium diet and Ca supplementation were recommended for local residents of Shenzhen to reduce the incidence of chronic diseases and promote a healthy lifestyle.

Compound-specific chlorine/bromine isotope analysis (CSIA-Cl/Br) has become a useful approach for degradation pathway investigation and source appointment of halogenated organic pollutants (HOPs). CSIA-Cl/Br is usually conducted by gas chromatography-mass spectrometry (GC-MS), which could be negatively impacted by chlorine and bromine isotope fractionation of HOPs on GC columns. In this study, 31 organochlorines and 4 organobromines were systematically investigated in terms of Cl/Br isotope fractionation on GC columns using GC-double focus magnetic-sector high resolution MS (GC-DFS-HRMS). On-column chlorine/bromine isotope fractionation behaviors of the HOPs were explored, presenting various isotope fractionation modes and extents. Twenty-nine HOPs exhibited inverse isotope fractionation, and only polychlorinated biphenyl-138 (PCB-138) and PCB-153 presented normal isotope fractionation. And no observable isotope fractionation was found for the rest four HOPs, i.e., PCB-101, 1,2,3,7,8-pentachlorodibenzofuran, PCB-180 and 2,3,7,8-tetrachlorodibenzofuran. The isotope fractionation extents of different HOPs varied from below the observable threshold (0.50%) to 7.31% (PCB-18). The mechanisms of the on-column chlorine/bromine isotope fractionation were tentatively interpreted with the Craig-Gordon model and a modified two-film model. Inverse isotope effects and normal isotope effects might contribute to the total isotope effects together and thus determine the isotope fractionation directions and extents. Proposals derived from the main results of this study for CSIA-Cl/Br research were provided for improving the precision and accuracy of CSIA-Cl/Br results. The findings of this study will shed light on the development of CSIA-Cl/Br methods using GC-MS techniques, and help to implement the research using CSIA-Cl/Br to investigate the environmental behaviors and pollution sources of HOPs., Comment: 30 pages, 5 figures

LC-MS/MS is currently the most selective and efficient tool for the quantitative analysis of drugs and metabolites in the pharmaceutical industry and in clinical assays. However, phase II metabolites sometimes negatively affect the selectivity and efficiency of the LC-MS/MS method, especially for the metabolites that possess similar physicochemical characteristics and generate the same precursor ions as their parent compounds due to the in-source collision-induced dissociation during the ionization process. This paper proposes some strategies for examining co-eluting metabolites existing in real samples, and further assuring whether these metabolites could affect the selectivity and accuracy of the analytical methods. Strategies using precursor-ion scans and product-ion scans were applied in this study. An example drug, namely, caffeic acid phenethyl ester, which can generate many endogenous phase II metabolites, was selected to conduct this work. These metabolites, generated during the in vivo metabolic processes, can be in-source-dissociated to the precursor ions of their parent compounds. If these metabolites are not separated from their parent compounds, the quantification of the target analytes (parent compounds) would be influenced. Some metabolites were eluted closely to caffeic acid phenethyl ester on LC columns, although long columns and relatively long elution programs were used. The strategies can be utilized in quantitative methodologies that apply LC-MS/MS to assure the performance of selectivity, thus enhancing the reliability of the experimental data.

Bioaccumulation and trophic transfer in ecosystems is an important criterion for assessing environmental risks of contaminants. This study investigated bioaccumulation and biomagnification of 13 organic ultraviolet absorbents (UVAs) in marine wildlife organisms in the Pearl River Estuary, South China Sea. The UVAs could accumulate in the organisms with biota - sediment accumulation factors (BSAF) of 0.003–2.152. UV531 was the most abundant and showed the highest tendency to accumulate in the organisms with a median BSAF of 1.105. The UVAs demonstrated species - and compound-specific accumulation in the marine organism. Fishes showed significantly higher capability than the cephalopods and crustaceans in accumulation of the UVAs. Habitat did not demonstrate obvious impact on accumulation of the UVA. On the other hand, benzophenone-3, UV328, and UV234 showed significantly higher concentration in the detritus feeding fishes than carnivorous and planktivorous fishes, suggesting governing effect of dietary habits of the organisms on bioaccumulation of these UVAs. Direct uptake from growth media was a significant exposure pathway of the organisms to the UVAs. The estimated trophic magnification factors and biomagnification factors revealed that UV329, UV531, and octocrylene could potentially biomagnify in the marine food web.

Two biomarkers, 5,9-dimethyl-6-isopropyl-2-decanone (1) and 4,9,11-trimethyl-6-isopropyl-2-dodecanone (2), were isolated from Chinese Maoming oil shale by silica gel column chromatography and preparative gas chromatography. Their structures were elucidated by using spectroscopic techniques.

This study presents a liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of chloroquine (CQ) and its metabolite desethyl chloroquine (DCQ) in human plasma. The method generally involved methanol protein precipitation and LC-MS/MS detection. The mass spectrometer was operated with positive electrospray ionization (ESI) source and the data acquisition was carried out in multiple reaction monitoring (MRM) mode. Quantification was performed by labeled isotope dilution method with matrix-matched calibration curves. Inter-batch accuracies were ranged from 90.2% to 109.8%. Both intra-batch and inter-batch precisions (relative standard deviation, RSD, %) of the analytes were no more than 15.0%. The recoveries were from 73.7% to 79.0%, and the limit of quantification (LOQ) was 1.0 and 0.5 ng/mL for CQ and DCQ, respectively. The linear ranges of CQ/DCQ were 1.0/0.5–500.0/250.0 ng/mL with the linear correlation coefficient R2 > 0.999. No significant matrix effect was ...

A reliable method was proposed for the simultaneous determination of five fluoroquinolones (FQs) and two tetracyclines (TCs) in sewage sludge using ultrasonic-assisted extraction (USE) followed by SPE cleanup and high-performance liquid chromatography-mass spectrometry (HPLC-MS)/MS analysis with electrospray ionisation (ESI) in a positive mode. The USE conditions (e.g. extraction solvent, pH, and extraction cycles) and high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) parameters were optimised. Quantification was performed by internal standard calibration in multiple reaction monitoring mode. Recoveries of the antibacterials ranged from 41 to 123%, with relative standard deviations within 17%. The sample-based limits of quantification were 10–63 ng g−1 dry weight (dw) for FQs (ciprofloxacin, enrofloxacin, lomefloxacin, norfloxacin, and ofloxacin) and 250–500 ng g−1 dw for TCs (tetracycline and oxytetracycline). The method was applied to determine the antibacterials in sewage slu...

A simple, reliable and sensitive method for the simultaneous determination of caffeic acid phenethyl ester (CAPE) and its metabolite caffeic acid (CA) in dog plasma was developed using liquid chromatography tandem mass spectrometry (LC–MS/MS). The sample pretreatment generally involved protein precipitation treatment (PPT) and direct dilution. CAPE and CA were separated with a C18 reversed-phase column. Electrospray ionization (ESI) interface operated in negative mode was chosen for ionization. Multiple reaction monitoring (MRM) mode was selected for data acquisition. The quantification range was 10.0–10,000.0 ng mL−1. The intra- and inter-batch accuracies were within 92.5–107.0% with relative standard deviation (RSD, %) no more than 10.5%. CAPE and CA were proved to be stable in stabilizer-treated dog blood and PPT-treated plasma during the sampling and pretreatment period. The applicability has been evaluated with real samples from treated dogs.

A sensitive method has been developed and validated for the determination of diverse groups of pharmaceuticals, steroid hormones, and hormone-like personal care products in sewage sludge. Samples were extracted by ultrasonic-assisted extraction followed by solid-phase extraction cleanup. For determination of estrogens and hormone-like phenolic compounds, sample extracts were further derivatized with dansyl chloride and purified with silica gel column chromatography to improve the analytical sensitivity. The chemicals were determined by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in multiple-reaction monitoring mode. Recoveries ranged mostly from 63% to 119% with relative standard deviations within 15%. Method quantification limits were 0.1-3 ng g(-1) dry weight (dw) for sewage sludge. The method was applied to a preliminary investigation of pharmaceuticals and personal care products (PPCPs) in sewage sludge and sediment in the Pearl River Delta, South China. Triclosan, triclocarban, 2-phenylphenol, bisphenol A, and parabens were ubiquitously detected at 3.6-5088.2 ng g(-1) dw in sludge and 0.29-113.1 ng g(-1) dw in sediment samples, respectively. Estrone, carbamazepine, metoprolol, and propranolol were also frequently quantified in the sludge and sediment samples. The dewatering process caused no significant losses of these PPCPs in sewage sludge.

A sensitive and feasible method was developed for the simultaneous determination of 10 trace antibiotic residues including sulfonamides, macrolides, trimethoprim, and chloramphenicol in sewage sludge and sediment. The method involved ultrasonic extraction followed by solid phase extraction cleanup and liquid chromatography-tandem mass spectrometry coupled with electrospray ionization in positive mode. The antibiotics were identified and determined by internal standard method in selected multiple reaction monitoring mode. The detection limits were in a range of 2.2–66.9 ng g−1 dry weight for the investigated antibiotic compounds in sewage sludge. The recoveries ranged from 74.7% to 111.8% with relative standard deviations of 1.2%–10.6%. The method was successfully applied to a primary investigation of the occurrence of antibiotic residues in a sewage sludge sample and a river sediment sample collected from Guangzhou. Sulfamethazine, trimethoprim, azithromycin, clarithromycin, dehydrated erythromycin, and roxithromycin were detected in both the sewage sludge and the river sediment, ranging from 6.8–125.6 ng g−1 dry weight.

Wastewater has proved to be a significant source of polybrominated diphenyl ethers (PBDEs) in the environment. Seventeen congeners from tri- to deca-BDEs were determined to characterize the occurrence, fate, and transport of PBDEs in two sewage treatment plants in the Pearl River Delta, South China. The PBDE concentrations varied substantially from 13.3 to 2496.4 ng L−1 in the raw wastewater, depending on the wastewater types and contents of the suspended particulate matter (SPM). The concentrations declined to 0.9 to 4.4 ng L−1 in the treated effluent and were closely associated with SPM contents. BDE-209 was the predominant congener in the wastewater and sewage sludge. Most of PBDEs might have ended up in the sewage sludge, with

The concentrations of three currently used non-polybrominated diphenyl ether (PBDE) brominated flame retardants (BFRs), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), decabromodiphenyl ethane (DBDPE), and tetrabromobisphenol A bis (2,3-dibromopropyl ether) (TBBPA-DBPE), were examined in environmental and biota samples collected from the Pearl River Delta (PRD) and an electronic waste (e-waste) area in southern China. We also examined deca-BDE (decabromodiphenyl ether) and nine tri- through hepta-BDE congeners for comparison. The results indicate that these non-PBDE BFRs occur widely in the environment of the two study areas. We found a noticeable increase in the levels of TBBPA-DBPE and DBDPE in recent sediments, the concentrations of which even exceed those of BDE209 (deca-BDE) in some samples from the PRD. The BFR profiles of the two study areas are distinct. Relatively high proportions of DBDPE and TBBPA-DBPE were found in the PRD environment, whereas the levels of discontinued BFRs (penta-BDEs and BDE183) and BTBPE were higher in the e-waste area. Our results suggest that the industrial activities in the PRD and the recycling of e-waste have introduced distinct types of BFR contamination to the ambient environment and deca-BDE product has been partly replaced by the TBBPA-DBPE and DBDPE in the PRD. Furthermore, BTBPE and DBDPE were detected in bird tissues and BTBPE in the fish tissues collected from the e-waste area. This is the first report of the occurrence of TBBPA-DBPE in environmental samples worldwide. More studies are needed for reaching a better understanding of the behavior, bioaccumulation, and toxicology of these increasingly used BFRs in the environment.

A scoping study was conducted to investigate the residues of nineteen pharmaceuticals and personal care products (PPCPs), including 4 natural and 3 synthetic steroid estrogens, 7 endocrine-disrupting phenols, and 5 acid pharmaceuticals in three urban streams and the Major Pearl River at Guangzhou, a megapolis in the Pearl River Delta, South China. Estrone was detected in >60% water samples with a maximum concentration of 65 ng L(-1). Endocrine-disrupting phenols (nonylphenol, bisphenol A, triclosan, 2-phenylphenol, methyparaben, and propylparaben) were found to be widely present at rather high concentrations in the urban riverine water of Guangzhou. Salicylic acid, clofibric acid and ibuprofen were detected in most water samples with maximum concentrations of 2098, 248 and 1417 ng L(-1) respectively, whereas naproxen was less frequently detected and also at lower concentration. Both the detection frequencies and median concentrations of the PPCPs appeared higher during the low-flow season than during the high-flow season. The seasonal difference in PPCPs occurrence was probably attributed to the dilution effect caused by the rainfall. PPCPs in the urban riverine water of Guangzhou originated mainly from random discharge and/or leakage of municipal wastewater. PPCPs contamination in the Major Pearl River may be of a potential environmental issue, especially during the low-flow season.

Three dated sedimentary cores were collected for the investigation of temporal trends and the environmental loadings of nonylphenol (NP) and bisphenol A (BPA) in recent decades in the Pearl River Estuary (PRE), South China and the adjacent South China Sea (SCS). The peak fluxes of NP and BPA occurred in the mid-1980s in the PRE, coincident with the rapid economic growth in China. The decline of NP and BPA fluxes is attributable to the implementation of sewage treatment in the late 1980s in the Pearl River Delta (PRD). Multi-model distributions were observed for the fluxes of NP and BPA in the SCS with the peak fluxes occurring in the late 1950s and the mid-1970s respectively. The fluxes of NP and BPA have increased since the 1990s due to the lack of adequate wastewater treatment facilities and the constant economic growth. Nonylphenol was quantifiably detected in sediments predating its widespread application (1940s), suggesting the downward penetration of NP in the sediment columns. The characterization results revealed that NP and BPA were preserved well and the isomer-selective degradation of NP did not occur significantly in the sediment cores. The environmental loadings of NP and BPA in the PRE sediments were roughly estimated to be 124 t and 1.7 t respectively over the past 30 years.

Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) are two perfluorinated compounds (PFCs) ubiquitously present in the environment, which could pose potential adverse effects on human health. Contamination and presence of PFOA and PFOS should be eliminated or rigidly restricted in food stuffs such as cooking oils and lard (from pig adipose tissue). This work describes a rapid, simple, reliable and sensitive method for quantitative analysis of PFOA and PFOS in cooking oils and pig adipose tissue with liquid chromatography tandem mass spectrometry (LC-MS/MS). The pretreatment mainly included a one-step reversed-phase liquid-liquid extraction using the mixture of basified water/methanol as the aqueous system, and dichloromethane (DCM) as the non-polar system. PFOA and PFOS can be successfully separated from the two lipid-rich matrices, i.e., cooking oil and adipose tissue, and extracted into the aqueous system, and then directly analyzed with LC-MS/MS. This method was validated in terms of accuracy (both intra- and inter-batch), precision, recovery, linearity, sensitivity and applicability. The intra-batch accuracies for PFOA and PFOS in cooking oil samples were within 93.9-101.9% with relative standard deviation (RSD) no more than 10.9%, and the inter-batch accuracies were 91.2-96.2% with RSD not exceeding 10.0%. The intra-batch accuracies of the analytes in pig adipose tissue samples were 102.9-113.0% with RSD of 8.8-13.1%. And the quantification ranges of PFOA and PFOS were 0.01-25ng/mL. This method has been applied to the analysis of PFOA and PFOS in real samples collected from local markets in Guangzhou, China.