Determination of polyfluoroalkyl substances in cosmetic products using dispersed liquid-liquid extraction coupled with UHPLC-MS/MS.

Human exposure to polyfluoroalkyl substances (PFASs) via cosmetics has been of increasing concern due to the tremendous detrimental health impacts of PFASs. Developing an effective method for extracting and determining PFASs in cosmetics is crucial in accurately assessing their corresponding human exposure risk. Herein, this study developed a new sample pre-treatment method to address the challenges posed by the variety and complexity of cosmetic matrices. Seventeen PFASs in cosmetic products, including 9 perfluoro carboxylic acids and 8 perfluorosulfonic acids, were simultaneously determined using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). The whole pre-treatment process can be divided into three steps. In step 1, cosmetics with diverse matrix types can be effectively dispersed during extraction by using saturated sodium chloride-acetonitrile and saturated sodium chloride-tetrahydrofuran as extraction solvents. In step 2, the pre-purification step employs a potassium ferrocyanide-zinc acetate co-precipitant to remove high molecular weight interferents from the extraction solution, thereby enhancing the efficiency of solid-phase extraction (SPE). In step 3, WAX-SPE is utilized to further eliminate interferents from the extraction solution while concentrating the analytes, meeting the trace analysis requirements for PFASs in cosmetics. The method detection limits were 0.09-0.26 ng g-1. The recoveries ranged from 70.1% to 114.7%, with relative standard deviations in the range of 2.0-19.1%. The method was applied to cosmetic samples in the Guangzhou market, and the total concentration of PFASs ranged from 0 to 10.8 ng g-1. This method has strong anti-interference ability, good applicability, high sensitivity, and good reproducibility, making it suitable for the analysis and detection of perfluorinated acids in cosmetic samples. It provides technical support for cosmetics safety regulation.

Metabolic Mechanism of Bacillus sp. LM24 under Abamectin Stress.

Abamectin (ABM) has been recently widely used in aquaculture. However, few studies have examined its metabolic mechanism and ecotoxicity in microorganisms. This study investigated the molecular metabolic mechanism and ecotoxicity of Bacillus sp. LM24 (B. sp LM24) under ABM stress using intracellular metabolomics. The differential metabolites most affected by the bacteria were lipids and lipid metabolites. The main significant metabolic pathways of B. sp LM24 in response to ABM stress were glycerolipid; glycine, serine, and threonine; and glycerophospholipid, and sphingolipid. The bacteria improved cell membrane fluidity and maintained cellular activity by enhancing the interconversion pathway of certain phospholipids and sn-3-phosphoglycerol. It obtained more extracellular oxygen and nutrients to adjust the lipid metabolism pathway, mitigate the impact of sugar metabolism, produce acetyl coenzyme A to enter the tricarboxylic acid (TCA) cycle, maintain sufficient anabolic energy, and use some amino acid precursors produced during the TCA cycle to express ABM efflux protein and degradative enzymes. It produced antioxidants, including hydroxyanigorufone, D-erythroascorbic acid 1'-a-D-xylopyranoside, and 3-methylcyclopentadecanone, to alleviate ABM-induced cellular and oxidative damage. However, prolonged stress can cause metabolic disturbances in the metabolic pathways of glycine, serine, threonine, and sphingolipid; reduce acetylcholine production; and increase quinolinic acid synthesis.

Tetrabromobisphenol A and hexabromocyclododecanes from interior and surface dust of personal computers: implications for sources and human exposure.

Tetrabromobisphenol A (TBBPA) and hexabromocyclododecane isomers (HBCDs) are widely detected in indoor environments, but the research on the accumulation, contamination, and human exposure of TBBPA and HBCDs in electronic products dust is still limited. It is unclear whether electronic products might pose human health risk via dust ingestion and dermal absorption. In this study, the levels and distributions of TBBPA and HBCDs were investigated in the personal computer (PC) interior dust and PC surface (upper and bottom) wipes. The median concentrations of TBBPA in PC interior dust, upper, and bottom surface wipes were 168.1 ng/g, 13.2 ng/m2, and 15.2 ng/m2, respectively. These levels were generally higher than those of HBCDs, which were 95.2 ng/g, 11.7 ng/m2, and 12.3 ng/m2, respectively. No significant correlations were found among the PC upper and bottom surface wipes, and interior dust, indicating different sources of TBBPA and HBCDs in PC interior and surface dust. The TBBPA and HBCDs in the PC interior dust were mainly released from inner PC materials, while the sources of target compounds on the surface wipes were likely from external environments. The exposure values of two occupational populations (including PC owners and PC repair workers) to TBBPA and HBCDs were measured by PC interior dust and upper surface wipes. The results imply dust ingestion (including hand-to-mouth uptake) is the main contributor of the exposure route to TBBPA and HBCDs for both PC owners and repair workers. Compared to PC owners, PC repair workers showed the greater risk in exposure assessment, which should be paid more attention.

Microbial community succession in response to sludge composting efficiency and heavy metal detoxification during municipal sludge composting.

This study researched microbial community succession in response to sludge composting efficiency and heavy metal detoxification during municipal sludge co-composting with spent mushroom and spent bleaching. The change law of key physicochemical properties, the heavy metals contents and forms during composting were analyzed, and the passivation of heavy metals after composting was explored. High-throughput sequencing was used to analyze the microbial community structure of treat 2 during composting, and the correlation analysis of microbial community structure with heavy metal contents and forms were carried out. The results showed that the sludge of each treatment reached composting maturity after 26 days of composting. Organic matter content, electrical conductivity, pH and seed germination index of treat 2 were all in line with the standard limit of agricultural sludge. Because of the presence of compost bacteria addition, the passivating heavy metals performance of treat 2 satisfied the standard limit of agricultural sludge after composting, which was superior to that of treat 1 and treat 3. The diversity of microbial communities in treat 2 decreased during composting. Extensive bacteria such as Bacillus, Geobacter, Lactobacillus, and Pseudomonas, which possessed the abilities of heavy metal passivation and organic oxidizing, were dominant in treat 2 during the heating stage. However, as composting proceeded, Tuberibacillus with ability of organic oxidizing gradually became the most dominant species at the thermophilic and cooling stages. Changes in microbial function varied from changes of microbial community in treat 2, subsequently affected the performances of heavy metal passivation and organic oxidizing during composting.

[Soil-crop Distribution and Health Risk Assessment of Organochlorine Pesticides on Typical Agricultural Land in Southern Leizhou Peninsula].

The residual content of organochlorine pesticides (OCPs) in soil and crops of typical agricultural land in the southern Leizhou peninsula were determined using gas chromatography-mass spectrometry (GC-MS). Additionally, the bioconcentration factors of organochlorine pesticides in eight crops were investigated, and the human health risk was evaluated. The results indicated that 10 types of OCPs were detected to varying degrees; HCHs and heptachlor were the main OCPs in the study area, with the residual contents of 23.83-111.51 ng·g-1 and 11.01-25.97 ng·g-1 in soil and 7.54-61.28 ng·g-1 and 3.96-30.97 ng·g-1 in crops, respectively. A small number of soil and crop samples were found to exceed the standard. The ratio of α-HCH/γ-HCH was less than 1 in 87.50% of the soil samples, and ß-HCH/α-HCH was larger than 1. This indicates that the HCHs were probably derived from the recent use of lindane and historical residual pollution, whereas the heptachlor was mainly derived from underground insect pests and the application of termite control agents. The enrichment ability of OCPs was significantly different among different crops. The bioaccumulation capacity of vegetables was higher than that of fruit. Furthermore, bulb vegetables (leeks) were significantly stronger than other vegetables. A human health risk assessment of OCPs showed that OCP-combined pollution would not cause significant health risks to the population in the study area. However, the maximum value of HI in some crop samples was greater than 1, indicating that there were still potential risks, which should not be ignored.

Human exposure and health risk assessment of an increasingly used antibacterial alternative in personal care products: Chloroxylenol.

The ban of some antibacterial ingredients, such as triclosan (TCS) and triclocarban (TCC), in personal care products (PCPs) in some countries (but not in China) has resulted in the increasing use of antibacterial alternatives, such as chloroxylenol (PCMX). However, the underlying human health risks and environmental impacts of PCMX exposure are largely unknown. Thus, the distribution characteristics of PCMX in PCPs and susceptible populations and the major routes and health risks of human exposure to PCMX were investigated. The PCMX, TCS, and TCC concentrations in PCPs, urine, drinking water, and surface water were determined using high-performance liquid chromatograph system equipped with diode array detector or triple quadrupole mass spectrometer. Results showed that PCMX is widely used in antibacterial hand sanitizers and household disinfectants in China. The addition of PCMX as an antibacterial ingredient in PCPs showed an increasing trend. The geomean concentrations of urinary PCMX in children and pregnant women were 21.6 and 31.9 µg·L-1, respectively, which were much higher than TCS and TCC. A considerable concentration of PCMX ranging from 1.62 to 9.57 µg·L-1 was observed in the aquatic environment, suggesting a potential massive-use of PCMX by humans. Human PCMX exposure via drinking was negligible because the PCMX concentrations in drinking water were less than 2.00 ng·L-1. During human simulation experiment, we found that dermal contact was the dominant route of human PCMX exposure, accounting for 92.1% of the urinary PCMX concentration. The estimated daily intake of PCMX in 9.68% of children and 5.66% of pregnant women was higher than the reference dose. However, the urinary 8-hydroxy-2'-deoxyguanosine concentrations remained stable despite the elevated PCMX concentrations, thereby suggesting that daily PCMX exposure may not cause oxidative DNA damage in humans. Nevertheless, the potential ecotoxicity and health risks induced by chronic PCMX exposure cannot be ignored because of its increasing use.

Brominated and phosphate flame retardants (FRs) in indoor dust from different microenvironments: Implications for human exposure via dust ingestion and dermal contact.

Indoor dust has been widely used to monitor flame retardants (FRs) in indoor environment, but most studies only focused on floor dust. In the present study, FRs were examined in indoor dust from different locations. Dust from air conditioner (AC) filters, beddings, floor, and windows in bedrooms, and dust from AC filters, printer table surface, computer table surface, floor, and windows in offices were collected, respectively. Polybrominated diphenyl ether congener 209 (BDE 209) and decabromodiphenyl ethane (DBDPE) were the most abundant brominated flame retardants (BFRs), and tris(chloroisopropyl) phosphate (TCIPP), tris(1,3-dichloroisopropyl) phosphate (TDCIPP), and triphenyl phosphate (TPHP) were the most abundant phosphate flame retardants (PFRs). In bedrooms, the AC filter dust had the highest median levels of BDE 209 (536 ng/g) and DBDPE (2720 ng/g), while bed dust had the highest median levels of ΣPFRs (2750 ng/g) among dust samples. In offices, printer table dust had higher median levels of BDE 209 (1330 ng/g), DBDPE (8470 ng/g), and ΣPFRs (11,000 ng/g) than those in other dust samples. The high dust ingestion values of BDE 209, DBDPE, and individual PFR were 0.28, 1.20, and <0.01-0.32 ng/kg bw/day and 7.37, 31.2, and <0.01-4.54 ng/kg bw/day for BDE 209, DBDPE, and individual PFR for adults and toddlers, respectively. The high dermal exposure values of individual PFR during sleeping were <0.01-0.23 and <0.01-0.36 ng/kg bw/day for adults and toddlers, respectively. More human exposure pathways other than dust ingestion should be considered, such as the dermal contact with beddings and furniture.

Alteration of Diastereoisomeric and Enantiomeric Profiles of Hexabromocyclododecanes (HBCDs) in Adult Chicken Tissues, Eggs, and Hatchling Chickens.

The concentrations and enantiomer fractions (EFs) of α-, ß-, and γ-hexabromocyclododecanes (HBCDs) were measured in chicken diet sources (soil and chicken feed), home-raised adult chicken (Gallus domesticus) tissues, eggs during incubation, and hatchling chicken tissues. HBCD concentrations were not detected-0.69 ng/g dry weight (dw) and 25.6-48.4 ng/g dw in chicken feed and soil, respectively. HBCDs were detected in all adult chicken tissues, except the brain, at median levels of 13.1-44.0 ng/g lipid weight (lw). The proportions of α-HBCD in total HBCDs increased from 51% in soil to more than 87% in adult chicken tissues. The accumulation ratios (ARs) of α-HBCD from diet to adult chicken tissues were 4.27 for liver, 11.2 for fat, and 7.64-12.9 for other tissues, respectively. The AR and carry-over rate (COR) of α-HBCD from diet to eggs were 22.4 and 0.226, respectively. The concentrations of α-HBCD in hatchling chicken liver (median: 35.4 ng/g lw) were significantly lower than those in hatchling chicken pectoral muscle (median: 130 ng/g lw). The EFs of α-HBCD decreased from soil to adult chicken tissues and from eggs to hatchling chicken liver. Meanwhile, the EFs of γ-HBCD increased from soil to adult chicken tissues. These results indicate the preferential enrichment of (-)-α-HBCD and (+)-γ-HBCD in chickens. The alteration of diastereoisomeric and enantiomeric patterns of HBCDs might be influenced by the different absorption and elimination rates of the six HBCD enantiomers as well as variations in HBCD metabolism in chickens.

Sorption of 3,3',4,4'-tetrachlorobiphenyl by microplastics: A case study of polypropylene.

Though plastics show good chemical inertness, they could sorb polychlorinated biphenyls (PCBs) and other toxic pollutants from the surrounding environment. Thus, ingestion of microplastics by marine organisms potentially enhances the transport and bioavailability of toxic chemicals. However, there is lack of studies on the sorption capacity, mechanism and factors affecting the sorption behavior. Here, sorption of PCBs by microplastics in the simulated seawater was studied using the batch oscillation equilibration technique, in which polypropylene (PP) and 3,3',4,4'-tetrachlorobiphenyl (PCB77) acted as model plastic and PCB, respectively. Factors including particle size, temperature and solution environment were investigated. Results showed that, equilibrium sorption time is about 8h and sorption capacity increase with decreasing particle size and temperature. Different sorption capacity in three solution environments was observed. Equilibrium data in three solution environments fitted very well to the Langmuir sorption model, indicating chemical sorption is the predominant mechanism.

[Pollution Characteristics and Ecological Risk Assessment of Organochlorine Pesticides in Water Source Areas of Guangdong and Guangxi].

The concentrations of 16 organochlorine pesticides (OCPs) in 7 water samples collected from different sites of water source areas of Guangdong and Guangxi were detected by SPE-GC-MS, and then the pollution characteristics were analyzed. This study established species sensitivity distribution(SSD) curves with BurrⅢ distribution model. In the meantime, HC5 values were calculated by BurrliOZ software, which were used to evaluate the toxicity effects of OCPs towards aquatic organisms. Finally, margin of safety concentration values were calculated to assess the ecological risk. The results showed that the concentration of OCPs varied from 6.64 to 34.19 ng·L-1, with a mean value of 16.76 ng·L-1, while HCHs and DDTs contributed a lot. HCHs were predominately originated from lindane, which is a component in household insecticide, while DDTs were from dicofol contamination or historical residues. Vertebrates could stand severer toxicity in comparison with invertebrates. α-endosulfan showed a greater toxicity towards aquatic plants and microorganisms than others, while p, p'-DDT turned out to be the most hazardous pollutant to vertebrates and invertebrates among the 16 OCPs studied. Generally speaking, OCPs in study areas didn't show conspicuous ecological risks towards aquatic organisms, DDTs and α-endosulfan, however, are still worth paying close attention due to their high potential risks.

Observation and confirmation of oxidation reactions occurring on ultra-high-performance liquid chromatography columns.

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-ß-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.

Occurrence, distribution and risk assessment of polychlorinated biphenyls and polybrominated diphenyl ethers in nine water sources.

Water quality of water sources is a critical issue for human health in South China, which experiences rapid economic development and is the most densely populated region in China. In this study, the pollution of organohalogen compounds in nine important water sources, South China was investigated. Twenty six organohalogen compounds including seventeen polychlorinated biphenyls (PCBs) and nine polybrominated diphenyl ethers (PBDEs) were detected using gas chromatograph analysis. The concentrations of total PCBs ranged from 0.93 to 13.07ngL(-1), with an average value of 7.06ngL(-1). The total concentrations of nine PBDE congeners were found in range not detected (nd) to 7.87ngL(-1) with an average value of 2.59ngL(-1). Compositions of PCBs and PBDEs indicated the historical use of Aroclors 1248, 1254 and 1260, and commercial PBDEs may be the main source of organohalogen compounds in water sources in South China. The nine water sources could be classified into three clusters by self-organizing map neural network. Low halogenated PCBs and PBDEs showed similar distribution in the nine water sources. Cancer risks of PCBs and PBDEs via water consumption were all below 10(-6), indicating the water quality in the nine water sources, South China was safe for human drinking.

[Simultaneous determination of nine pharmaceuticals personal care products in waters by solid phase extraction-gas chromatography-mass spectrometry].

An analytical method has been developed and validated for the simultaneous determination of nine pharmaceuticals and personal care products (PPCPs) in water samples, including salicylic acid, naproxen, ibuprofen, paracetamol, clofibric acid, triclosan, diclofenac, ketoprofen, bisphenol A. The qualification and quantification of the target compounds were performed by gas chromatography-mass spectrometry in selected ion monitoring mode (GC-MS-SIM). The water samples were concentrated and purified through Oasis HLB cartridges after the pH value of the water was adjusted to 3, then derivatized with trimethyl sulfonium hydroxide (TMSH) at room temperature, and determined by GC-MS-SIM using 2,4,5-fenoprop as internal standard. The conditions for sample pretreatment (e. g. solid phase extraction and derivatization) were studied. Under the optimized conditions, the recoveries were ranged from 50.7% to 115.4% with the relative standard deviations lower than 10%. The limits of detection were in the range of 0.03-0.30 microg/L and the limits of quantification were in the range of 0.15-1.50 microg/L. The method has been successfully applied to monitor the occurrence of the PPCPs residues in agricultural irrigation water in Dongguan, Guangdong Province. The four compounds were detected at maximum mass concentration range of 0.176-0.998 microg/L. It proved that this analytical method is sensitive, reliable and acceptable.

[Distribution characteristics of polycyclic aromatic hydrocarbons and black carbon in road dusts from typical cities of China and India].

In order to investigate the distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) in road dusts in typical cities of Beijing, Shanghai, Guangzhou and Wuhan in China and Kolcata in India, samples were collected in urban roads during Dec., 2007 to Feb., 2009. The total 16 PAHs concentrations in metro cities from China were 2.30-22.2 microg x g(-1), which was dominated by FLA, PHE, PYR, CHR, BBF and BGP. PAHs contents were in the range of 4.85-30.5 microg x g(-1) in Kolcata from India, which was dominated by NAP. Higher levels of BC in Chinese cities than India city were likely due to different power structures and consumes. The correlation between PAHs and BC showed different characteristics in different city, which might be reflected diverse sources. Diagnostic ratios demonstrated that the main source of PAHs was from the emission of vehicle, and coal combustion is another possible source.

[Characterization of polycyclic aromatic hydrocarbons contaminations in surface sediments from Zhalong wetland, China].

Soxhlet extraction, silica gel alumina column for separation and clean up and gas chromatography-mass spectrometer (GC-MS) for qualitative and quantitative analysis were used for study environmental behavior of 15 priority PAHs of twelve surface sediment samples collected from Zhalong wetland, Heilongjiang Province. The objectives of this study were to identify the PAHs contamination level, composition pattern, pollution sources and pathways, and to assess the ecological risk of PAHs to aquatic life in Zhalong wetland. The total concentrations of 15 priority PAHs ranged form 31.9 to 290 ng/g (dry weight), with a mean value of 130 ng/g. The PAHs profiles were dominated by two-to four-ring compounds which accounted for 90% of total PAHs. Phenanthrene, fluorine, fluoranthene, and pyrene represented the highest fractions in all surface sediment samples. Comparing with other results from wetlands and lakes in China or other countries, the PAH concentrations level in Zhalong wetland surface sediments were relatively low, in the same range of Lharu wetland. The linear regression analysis showed that the concentrations of PAHs were significantly correlated to the sediment total organic carbon (TOC) content (R2 = 0.87). PAHs contamination might mainly came from biomass and coal combustion. After long range atmospheric transport and deposition, the released PAHs finally accumulated into wetland sediment. Ecology risk assessment indicated that phenanthrene and fluorine had exhibited a tendency of accumulation on surface sediment of Zhalong wetland, which would exert negative toxic effect on aquatic organism.