Comprehensive analysis of phospholipid in milk and their biological roles as nutrients and biomarkers.

Phospholipids (PL) have garnered significant attention due to their physiological activities. Milk and other dairy products are important dietary sources for humans and have been extensively used to analyze the presence of PL by various analytical techniques. In this paper, the analysis techniques of PL were reviewed with the eight trigrams of phospholipidomics and a comprehensive fingerprint of 1295 PLs covering 8 subclasses in milk and other dairy products, especially. Technology is the primary productive force. Based on phospholipidomics technology, we further review the relationship between the composition of PL and factors that may be involved in processing and experimental operation, and emphasized the significance of the biological role played by PL in dietary supplements and biomarkers (production, processing and clinical research), and providing the future research directions.

Bisphenol A Analogues Induce Neuroendocrine Disruption via Gut-Brain Regulation in Zebrafish.

There is epidemiological evidence in humans that exposure to endocrine-disrupting chemicals such as bisphenol A (BPA) is tied to abnormal neuroendocrine function with both behavioral and intestinal symptoms. However, the underlying mechanism of this effect, particularly the role of gut-brain regulation, is poorly understood. We exposed zebrafish embryos to a concentration series (including environmentally relevant levels) of BPA and its analogues. The analogue bisphenol G (BPG) yielded the strongest behavioral impact on zebrafish larvae and inhibited the largest number of neurotransmitters, with an effective concentration of 0.5 µg/L, followed by bisphenol AF (BPAF) and BPA. In neurod1:EGFP transgenic zebrafish, BPG and BPAF inhibited the distribution of enteroendocrine cells (EECs), which is associated with decreased neurotransmitters level and behavioral activity. Immune staining of ace-α-tubulin suggested that BPAF inhibited vagal neural development at 50 and 500 µg/L. Single-cell RNA-Seq demonstrated that BPG disrupted the neuroendocrine system by inducing inflammatory responses in intestinal epithelial cells via TNFα-trypsin-EEC signaling. BPAF exposure activated apoptosis and inhibited neural developmental pathways in vagal neurons, consistent with immunofluorescence imaging studies. These findings show that both BPG and BPAF affect the neuroendocrine system through the gut-brain axis but by different mechanisms, revealing new insights into the modes of bisphenol-mediated neuroendocrine disruption.

Novel Platinum-Nickel Composite Trap for Simultaneous and Direct Determination of Mercury and Cadmium in Soil and Its Mechanism Study.

In this work, following a metal-ceramic heater (MCH) as an electrothermal vaporizer (ETV), a novel composite Pt/Ni trap based on platinizing the foamed nickel was first fabricated to trap Hg and Cd simultaneously. So, a solid sampling Hg-Cd analyzer was developed to simultaneously detect trace Hg and Cd in soil samples, mainly consisting of an MCH, a composite Pt/Ni trap, and an atomic fluorescence spectrometer (AFS). This small-size MCH-ETV system only consumes 100 W for the complete vaporization of Hg and Cd in soil matrices. The Pt/Ni trap fulfills the complete trapping of Hg and Cd following the solid sampling MCH-ETV system and then fast releases them by heating. It was proved that trapped and released Hg and Cd by the Pt/Ni trap are atomic species using X-ray photoelectron spectroscopy (XPS) and other approaches; specially, the effective cotrapping of Hg and Cd might be due to forming alloys of Hg + Pt and Cd + Ni on the Pt/Ni trap. Under the optimized conditions, the method detection limits (LODs) of Hg and Cd reached 0.4 µg/kg and 0.04 µg/kg for a 20 mg sample size, the relative standard deviations (RSDs) were within 12% and 8% for soil samples, respectively, and the recoveries ranged from 96% to 105%, indicating favorable analytical sensitivity, precision, and accuracy. The whole analysis time can be controlled within 5 min without the soil digestion process. The proposed Hg-Cd analyzer is thus suitable for rapid detection of Hg and Cd in soil samples with advantages such as simplicity, green, and safety. Further, the proposed solid sampling ETV-composite trap method has a promising application potential in the field and rapid detection for multielements.

Maternal transfer of florfenicol impacts development and disrupts metabolic pathways in F1 offspring zebrafish by destroying mitochondria.

Maternal exposure to antibiotics existing in the environment is a predisposing factor for developmental malformation with metabolic disorders in offspring. In this study, female zebrafish (3 months) were exposed to 0.05 mg/L and 0.5 mg/L florfenicol (FF) for 28 days. After pairing and spawning with healthy male fish, F1 embryos were collected and developed to 5 d post-fertilization (dpf) in clear water. And the adverse effects on the F1 generation were examined thoroughly. The fecundity of F0 female fish and the hatchability, mortality, and body length of F1 larvae significantly decreased in the treatment group. Meanwhile, multi-malformation types were found in the exposure group, including delayed yolk sac absorption, lack of swim bladder, and spinal curvature. Metabolomic and transcriptomic results revealed alterations in metabolism with dysregulation in tricarboxylase acid cycle, amino acid metabolism, and disordered lipid metabolism with elevated levels of glycerophospholipid and sphingolipid. Accompanying these metabolic derangements, decreased levels of ATP and disordered oxidative-redox state were observed. These results were consistent with the damaged mitochondrial membrane potential and respiratory chain function, suggesting that the developmental toxicity and perturbed metabolic signaling in the F1 generation were related to the mitochondrial injury after exposing F0 female zebrafish to FF. Our findings highlighted the potential toxicity of FF to offspring generations even though they were not directly exposed to environmental contaminants.

Combined lethal toxicity, biochemical responses, and gene expression variations induced by tebuconazole, bifenthrin and their mixture in zebrafish (Danio rerio).

Pesticides commonly occur as mixtures in an aqueous environment, causing deleterious effects on human health and the environment. However, the mechanism underlying the combined effects on aqueous organisms remains largely unknown, especially at low concentrations. In the current study, we inspected the interactive toxicity of tebuconazole (TEB), a triazole fungicide, and bifenthrin (BIF), a pyrethroid insecticide, to zebrafish (Danio rerio) using various toxicological assays. Our data revealed that the 96 h-LC50 (lethal concentration 50) values of BIF to fish at different life periods (embryonic, larval, juvenile, and adult periods) ranged from 0.013 (0.011-0.016) to 0.41 (0.35-0.48) mg a.i. L-1, which were lower than that of TEB ranging from 1.1 (0.88-1.3) to 4.8 (4.1-5.7) mg a.i. L-1. Combination of TEB and BIF induced synergetic acute toxicity to embryonic fish. Activities of T-SOD, POD, and GST were distinctly altered in most individual and joint administrations. Expressions of 16 genes associated with oxidative stress, cellular apoptosis, immune system, and endocrine system at the mRNA level were evaluated, and the information revealed that embryonic zebrafish were impacted by both individual compounds and their combinations. Six genes (cas9, P53, gr, TRα, IL-8, and cxcl-clc) exhibited greater changes when exposed to pesticide mixtures. Therefore, the joint effects induced by the pesticides at low concentrations should be considered in the risk assessment of mixtures and regulated as priorities for mixture risk management in the aqueous ecosystem. More research is needed to identify the threshold concentrations of the realistic pesticide mixtures above which synergistic interactions occur.

Integrated metabolomics and transcriptomics analysis reveals new biomarkers and mechanistic insights on atrazine exposures in MCF­7 cells.

Atrazine (ATZ) is a widely used herbicide worldwide and is a long-suspected endocrine-disrupting chemical. However, most endocrine-disrupting toxicity studies on ATZ have been based on animal models and those investigating inner mechanisms have only focused on a few genes. Therefore, the possible link between ATZ and endocrine-disrupting toxicity is still unclear. In this study, multi-omics and molecular biology techniques were used to elucidate the possible molecular mechanisms underlying the effect of ATZ exposure on MCF-7 proliferation at environmentally relevant concentrations. Our study is the first report on ATZ-induced one carbon pool by folate metabolic disorder in MCF-7 cells. A concentration of 1 µM ATZ yielded the highest cell viability and was selected for further mechanistic studies. A total of 34 significantly changed metabolites were identified based on metabolomic analysis, including vitamins, amino acids, fatty acids, and corresponding derivatives. Folate and pyridoxal have potential as biomarkers of ATZ exposure. One carbon pool by folate metabolic pathway was identified based on metabolic pathway analysis of the significantly altered pathways. Moreover, FTCD and MTHFD related to this pathway were further identified based on transcriptomic analysis and protein assays. Folate and different forms of 5,6,7,8-tetrahydrofolate, which participate in purine synthesis and associate with methyl groups (SOPC, arachidonic acid, and L-tryptophan) in one carbon pool by the folate metabolic pathway, potentially promote MCF-7 cell proliferation. These findings on the key metabolites and regulation of the related differentially expressed genes in folate metabolism will shed light on the mechanism of MCF-7 cell proliferation after ATZ exposure. Overall, this study provides new insights into the mechanistic understanding of toxicity caused by endocrine-disrupting chemicals.

Polyethyleneimine-modified magnetic carbon nanotubes as solid-phase extraction adsorbent for the analysis of multi-class mycotoxins in milk via liquid chromatography-tandem mass spectrometry.

Polyethyleneimine-modified magnetic multi-walled carbon nanotubes were developed to extract 10 mycotoxins. Simple modification of polyethyleneimine was achieved on the magnetic substrate by using an epoxy-containing silane agent as a linker. The resultant magnetic adsorbent was integrated with reverse phase and anion exchange interaction sites. Under optimal extraction conditions, only 20.0 mg adsorbent was used to extract the mycotoxins from 50.0 mL loading solution. The maximum adsorption capacities of the adsorbent toward the mycotoxins ranged from 4.9 to 10.2 mg/g. Adsorption and desorption were completed within 3.0 and 2.0 min, respectively. The adsorbent could be used for six repeated runs without evident change in extraction performance. The adsorbent combined with liquid chromatography-tandem mass spectrometry was applied further to analyze the mycotoxins in milk. The absolute recoveries of the 10 mycotoxins ranged from 88.3 to 103.5% with relative standard deviations that ranged from 2.4 to 6.5%, and their limits of detection were 0.003 to 0.442 µg/kg. The proposed adsorbent has great potential in the routine analysis of mycotoxins in ordinary analytical chemistry laboratory.

Toxic effects of fipronil and its metabolites on PC12 cell metabolism.

Fipronil and its metabolites (fipronil sulfone, fipronil sulfide and fipronil desulfinyl) adversely affect the environment and human health. Targeted metabolomics and lipidomics based on ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to analyse the alterations of glycerophospholipids and amino acids after exposure to fipronil and its metabolites at dosages of 0.5, 12.5 and 50 µM for 72 h and to evaluate their different toxic effects. Results showed that fipronil sulfone and fipronil desulfinyl are more toxic than their parent compound, with fipronil desulfinyl as the most toxic and fipronil sulfide as the least toxic. Fipronil and its metabolites affected the metabolism of PC18:1/16:0, PI18:0/20:4, arginine, leucine and tyrosine and the "phenylalanine, tyrosine and tryptophan biosynthesis" pathway, indicating their possible inducing role in cellular macromolecule damage, nerve signal transmission disturbance and energy metabolism disruption caused by oxidative stress. Importantly, fipronil sulfone and fipronil desulfinyl more strongly influenced lipid and amino acid metabolism, mainly reflected in the number of changed glycerophospholipids and differential metabolites associated with oxidative stress, including PS18:0/20:4, glutamate, phenylalanine and histidine for fipronil sulfone and PS18:0/20:4, glutamate, phenylalanine, serine and aspartic acid for fipronil desulfinyl. Therefore, the higher toxicity of fipronil desulfinyl and fipronil sulfone may be also related to oxidative stress. This study provides implications for risk assessment and toxic mechanism research on fipronil and its metabolites.

High Sensitivity Analysis of Selenium by Ultraviolet Vapor Generation Combined with Microplasma Gas Phase Enrichment and the Mechanism Study.

Ultraviolet vapor generation (UVG), as an environmental/user-friendly and efficient sampling approach, was first combined with the gas phase enrichment of Se by dielectric barrier discharge (DBD) microplasma. Volatile Se species from UVG, being much more complicated than conventional hydrides, can be trapped quantitatively (∼100%) on the quartz surface of DBD tube under O2-containing atmosphere and released (∼100%) under H2-containing atmosphere. The absolute detection limit (LOD) for Se was 4 pg (injection volume = 1.2 mL), and the linear (R2 > 0.995) range was 0.05-50 µg/L. The results were in good agreement with those of certified reference materials (CRMs) of water and soil samples, and spiked recoveries for real samples were 90-102% with 1-10% relative standard deviations (RSDs). By gas phase analyte enrichment, the proposed method improved analytical sensitivity (peak height) by 16 times. The mechanism was deduced that dominating SeCO species besides H2Se generating from UVG were all trapped on the DBD quartz tube surface as SeO2 or selenite and then released/transported as atoms to the detection zone. The combination of UVG and DBD can facilitate the green uses, miniaturization, and portability revealing its promising potential in field elemental analysis.

Changes in thyroid hormone levels and related gene expressions in embryo-larval zebrafish exposed to binary combinations of bifenthrin and acetochlor.

Bifenthrin (BF) and acetochlor (AT) are widely used as an insecticide and herbicide, respectively, which are introduced to the aquatic environment as a natural result. Although the thyroid active substances may coexist in the environment, their joint effects on fish have not been identified. We examined the joint toxicity of BF and AT in zebrafish (Danio rerio) in this study. An acute lethal toxicity test indicated that the median lethal concentration (LC50) values of BF and AT under 96 h treatment were 0.40 and 4.56 µmol L-1, respectively. The binary mixture of BF + AT displayed an antagonistic effect on the acute lethal toxicity. After 14 days post fertilization (dpf) with exposure to individual pesticides at sub-lethal concentrations of, no effects were observed on the catalase (CAT) and peroxidase (POD) activities, while the binary mixtures (except for the 7.2 × 10-3 µmol L-1 BF + 1.2 × 10-2 µmol L-1 AT exposure group) significantly induced the CAT activity. The superoxide dismutase (SOD) activity and triiodothyronine (T3) level were significantly increased in all exposure groups. The thyroxine (T4) level remained unchanged after exposure to individual pesticides, but significantly increased in the 7.2 × 10-3 µmol L-1 BF + 1.2 × 10-2 µmol L-1 AT group. The expressions of the genes Dio2, TRa, TSHß and CRH in the thyroid hormone (TH) axis were significantly up-regulated in the 7.2 × 10-3 µmol L-1 BF + 0.4 × 10-2 µmol L-1 AT group. Our data indicated that the binary mixture of BF + AT significantly altered the antioxidant enzyme activities and gene expressions in the hypothalamic-pituitary-thyroid (HPT) axis and changed the TH levels.

Amphiphilic block copolymer-grafted magnetic multi-walled carbon nanotubes as QuEChERS adsorbent for simultaneous determination of mycotoxins and pesticides in grains via liquid chromatography tandem mass spectrometry.

An amphiphilic block copolymer consisting of poly(N-acryloyl-glucosamine) (PAGA) and poly(tert-butyl methacrylate) (PtBMA) was designed and grafted on magnetic multi-walled carbon nanotubes (Fe3O4MWCNTs). The resultant Fe3O4MWCNTs@copolymer was proposed as QuEChERS adsorbent for determination of 15 mycotoxins and 25 pesticides in grains via liquid chromatography tandem mass spectrometry. The adsorbent was characterized by a transmission electron microscope, scanning electron microscope, elemental analysis, and other techniques. The common matrix interferences were efficiently removed by the proposed adsorbent, such as pigment, fatty acids, and the saccharide. PAGA segment played an important role in removing the hydrophilic interferences through hydrogen bonding due to the high density of hydroxyl groups. PtBMA segment removed the fatty residues through its strong hydrophobic carbon moiety. In comparison with the commercially available QuEChERS adsorbents, the proposed adsorbent had higher adsorption capacities towards the typical matrix interferences. To achieve satisfactory recoveries of analytes, various parameters in the QuEChERS procedure were comprehensively investigated. Under the optimal conditions, 95.0% of the analytes showed satisfactory recoveries in the range 70.0-120% as well as negligible matrix effects. The limits of detection (LOD) were in the range 0.00015-1.3 µg kg-1. Compared with previously reported QuEChERS methods, the proposed method had improved sensitivity and benefited from low matrix effects. The recoveries of analytes in various grains were in the range 60.8-108% with relative standard deviations (RSD) less than 13%. Moreover, the Fe3O4MWCNTs@copolymer exhibited good synthetic reproducibility and rapid magnetic separation (less than 10 s). The research provides a versatile platform to develop multi-functional QuEChERS adsorbents based on the amphiphilic block copolymer.

Single-Molecule Kinetic Fingerprinting for the Ultrasensitive Detection of Small Molecules with Aptasensors.

Aptamers have emerged as promising molecular tools for small-molecule analyte sensing. However, the performance of such aptasensors is generally limited by leakage since it has been difficult to completely suppress signal in the absence of analyte, resulting in a compromise between sensitivity and specificity. Here, we describe a methodology for the ultrasensitive detection of analytes combining aptasensors with single-molecule kinetic fingerprinting. A short, fluorescently labeled DNA probe is utilized to detect the structural changes upon ligand binding to the designed hairpin-shaped aptasensor probe. The Poisson statistics of binding and dissociation events of the DNA probe to single surface-immobilized aptasensor molecules is monitored by total internal reflection fluorescence microscopy, permitting the high-accuracy discrimination of the ligand bound and ligand-free states, resulting in zero background. The programmable dynamics of the hairpin enables fine-tuning of the hybridization kinetics of the fluorescent probe, rendering the acquisition time sufficiently flexible to optimize discrimination. Remarkable detection limits are achieved for a diverse set of analytes when spiked into chicken meat extract: the nucleotide adenosine (0.3 pM), the insecticide acetamiprid (0.35 pM), and the dioxin-like toxin PCB-77 (0.72 pM), which is superior to recently reported aptasensors. Our generalizable method significantly improves the performance of aptasensors, with the potential to extend to other molecular biomarkers.

Combined anti-androgenic effects of mixtures of agricultural pesticides using in vitro and in silico methods.

Humans and wildlife are continuously and simultaneously exposed to various pesticides that have been identified as endocrine disruptors which interfere with regulations of sexual differentiation and fertility. Low-dose effects of combined exposure from mixtures of pesticides have been extensively reported and need to be addressed in the context of human health risk assessment. The objective of the study is to assess the individual and combined anti-androgenic effects of twelve widely used pesticides in MDA-kb2 cells. The order of potency for seven pesticides with moderate anti-androgenic activities was in the order: fenitrothion > dimethomorph > difenoconazole > bromopropylate > prochloraz > imazalil > endosulfan, which was induced by the androgen receptor (AR) antagonism rather than cytotoxicity (with the exception of endosulfan which exhibited the highest cytotoxicity). The other five pesticides exhibited lower anti-androgenic activities. At 10% of AR antagonistic effect, three mixtures comprised of the seven pesticides (Mix-EC10, Mix-EC20, and Mix-EC25) at equi-effect concentrations showed summed concentrations of 6.75E-11, 17.63 and 25.21 µM, respectively. The combined effects were essentially close to the predicted of concentration addition (CA) at realistically low concentrations. In addition, molecular docking simulation indicated that hydrophobic interaction and polar functional groups of the pesticides contributed to the binding energy, which might be responsible for the AR antagonism. Our findings provide a basis for defining similarly acting antagonists in the context of cumulative risk assessment for pesticides in foods.

Analysis of glycerophospholipid metabolism after exposure to PCB153 in PC12 cells through targeted lipidomics by UHPLC-MS/MS.

Polychlorinated biphenyls (PCBs) are persistent organic pollutants (POPs) that have neurotoxicity, reproductive toxicity, hepatotoxicity and immunotoxicity in both animals and humans. Few studies have focused on the changes to endogenous glycerophospholipid metabolism caused by PCB153. To evaluate the relationships between exposure to PCB153 and specific endogenous glycerophospholipid metabolism, an ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was implemented in this study. Twenty-two endogenous glycerophospholipids in PC12 cells were analyzed after exposure to PCB153 at dosages of 0.05 µg mL-1, 0.5 µg mL-1 or 20 µg mL-1 for 120 h. PC(14:0/14:0), PE(16:0/18:1), PE(16:0/18:2), PS(18:0/18:1) and PI(16:0/18:1) were identified as potential biomarkers under the rules of t-test (P) value < 0.05 and variable importance at projection (VIP) value > 1. It was also found that the alterations at 0.05 µg mL-1 and 20 µg mL-1 PCB153 were similar at 120 h, while 0.5 µg mL-1 PCB153 presented an opposite trend. Additionally, significant upregulation of PC, PE and PS with the same fatty acid chains of 18:0/18:2 was found after exposure to 0.05 µg mL-1 and 20 µg mL-1 PCB153 at 120 h. This study revealed that PCB153 exposure modulated 22 endogenous glycerophospholipids in PC12 cells and provided the basis for the further study of PCB153 on the effects of glycerophospholipids on PC12 cells.

In Situ Dielectric Barrier Discharge Trap for Ultrasensitive Arsenic Determination by Atomic Fluorescence Spectrometry.

The mechanisms of arsenic gas phase enrichment (GPE) by dielectric barrier discharge (DBD) was investigated via X-ray photoelectron spectroscopy (XPS), in situ fiber optic spectrometer (FOS), etc. It proved for the first time that the arsenic species during DBD trapping, release, and transportation to the atomic fluorescence spectrometer (AFS) are probably oxides, free atoms, and atom clusters, respectively. Accordingly, a novel in situ DBD trap as a GPE approach was redesigned using three-concentric quartz tube design and a modified gas line system. After trapping by O2 at 9.2 kV, sweeping for 180 s, and releasing by H2 at 9.5 kV, 2.8 pg detection limit (LOD) was achieved without extra preconcentration (sampling volume = 2 mL) as well as 4-fold enhancement in absolute sensitivity and ∼10 s sampling time. The linearity reached R2 > 0.998 in the 0.1-8 µg/L range. The mean spiked recoveries for tap, river, lake, and seawater samples were 100-106%; and the measurements of the certified reference materials (CRMs) were in good agreement with the certified values. In situ DBD trap is also suitable to atomic absorption spectrometry (AAS) or optical emission spectrometry (OES) for fast and on-site determination of multielements.

Simultaneous determination of amantadine and rimantadine in feed by liquid chromatography-Qtrap mass spectrometry with information-dependent acquisition.

A sensitive method for simultaneous determination of amantadine and rimantadine in feed was developed using an ultra-high-performance liquid chromatography-triple quadrupole linear ion trap mass spectrometry (UHPLC-Qtrap-MS) in the multiple reaction monitoring information-dependent acquisition-enhanced product ion (MRM-IDA-EPI) mode, and employing the mixed cation exchange (MCX) solid-phase extraction column as sample cleanup and amantadine-d15 and rimantadine-d4 as internal standards, respectively. Compared to traditional MRM mode, for the targeted drugs in feed simultaneously both the secondary mass spectra and MRM information can be obtained using UHPLC-Qtrap-MS with MRM-IDA-EPI mode, and thus more accurate qualitative confirmation results achieved even at lower concentration of 0.2 µg/L in acceptable purity fit values. After optimization of sample preparation, good linearities (R > 0.9994) were obtained over the concentration range from 1 to 200 µg/L for amantadine and rimantadine. The precision was validated by intra-day and inter-day, and the relative standard deviations were all within 9.61%. Mean recoveries ranged from 76.1 to 112% at spiked concentrations of 0.5-100 µg/kg in three types of feed samples, including formula feed and complex concentrated feed for pigs and premix feed for chicken. The limits of detection (LODs) and quantification (LOQs) were 0.2 and 0.5 µg/kg for both drugs, respectively. The application in real feed samples further proved the accuracy and reliability of the developed method. This method provides an important tool to detect illegal uses of amantadine and rimantadine in feed. Graphical abstract Simultaneous quantitation and qualitative confirmation of amantadine and rimantadine in feed by MRM-IDA-EPI.

Determination of synephrine in feeds by a novel quick, easy, cheap, effective, rugged, and safe solid-phase extraction method combined with UHPLC-MS/MS.

To detect and quantify synephrine in feed, an effective analytical method based on quick, easy, cheap, effective, rugged, and safe solid-phase extraction coupled to ultra high performance liquid chromatography with tandem mass spectrometry was developed with isotopic internal standards. Pretreatment was performed using quick, easy, cheap, effective, rugged, and safe solid-phase extraction with primary secondary amine and C18 sorbent as sorbents in combination with Oasis MCX column clean-up to extract and purify feed samples. Tandem mass spectrometry detection in positive ion mode was conducted in positive multiple reaction monitoring mode in addition to the quantitative internal standard method. Two transitions of synephrine at m/z 168.1/150.0 and 168.1/135.0 were selected, and m/z 168.1/135.0 was determined as the quantification ion pair. D9 -Terbutaline was selected as an internal standard, for which m/z 235.1/153.0 was selected as the quantification ion pair. Good linearity was shown for synephrine in the range of 0.5-50 µg/L, and the correlation coefficient exceeded 0.999. The recoveries in three different feed samples at three spiked levels were 81.42-112.08%, and the relative standard deviations were not greater than 14.66%. The method proposed in this study was reliable and highly effective, and its sensitivity, accuracy, and precision are suitable for determining synephrine residues in feed samples.

Mixture toxicity of four commonly used pesticides at different effect levels to the epigeic earthworm, Eisenia fetida.

As commonly used pesticides, chlorpyrifos (CPF), fenobucarb (FEN), clothianidin (CLO) and acetochlor (ACE) are widely applied on crops worldwide. In this study, the combined toxicities of their binary, ternary and quaternary mixtures were evaluated using the earthworm Eisenia fetida as test organism. Mixture toxicities were studied using the combination index (CI) method and visualized by isobolograms, and then data were compared with traditional concentration addition (CA) and independent action (IA) models. Two binary mixtures of CPF+FEN and FEN+ACE, two ternary mixtures of CPF+CLO+FEN and CPF+FEN+ACE, and quaternary mixture of CPF+FEN+ACE+CLO exhibited a clear synergistic effect. The CI method was compared with the classical models of CA and IA, indicating that the CI method could accurately predict the combined toxicities of the chemicals. The results indicated that it was difficult to predict combined effects of these pesticides from mode of action alone because of existence of complicated synergistic and antagonistic responses. More attention should be paid to the potential synergistic effects of chemicals interactions, which might cause serious ecological problems.

Occurrence and dietary exposure assessment of PFOS and PFOA in cultured Trachinotus ovatus in China.

In this study, investigation was conducted into concentrations of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in Chinese farmed Trachinotus ovatus between 2014 and 2015 using a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) and ultra fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method. The tissue distribution (muscle, skin, liver, kidney and gill) in Trachinotus ovatus was also assessed. The detection frequencies of PFOS and PFOA in fish were 92% and 3%, respectively, and the mean concentrations were 0.392 and 0.015 µg/kg wet weight. The analysis of PFOS distribution in different tissues in Trachinotus ovatus showed the following trend: skin> gill> kidney> liver> flesh. Results revealeded farmed Trachinotus ovatus in China to generally be contaminated with PFOS. Moreover, the average daily intake for Chinese urban residents calculated on the basis of pollution content was 0.268 ng/kg body weight/d (PFOS) and 0.014 ng/kg body weight /d (PFOA), respectively. Both hazard ratio values were less than 1, indicating that exposure levels of PFOS and PFOA through Trachinotus ovatus consumption may not lead to adverse health effects in the Chinese population.

Ambient-Temperature Trap/Release of Arsenic by Dielectric Barrier Discharge and Its Application to Ultratrace Arsenic Determination in Surface Water Followed by Atomic Fluorescence Spectrometry.

A novel dielectric barrier discharge reactor (DBDR) was utilized to trap/release arsenic coupled to hydride generation atomic fluorescence spectrometry (HG-AFS). On the DBD principle, the precise and accurate control of trap/release procedures was fulfilled at ambient temperature, and an analytical method was established for ultratrace arsenic in real samples. Moreover, the effects of voltage, oxygen, hydrogen, and water vapor on trapping and releasing arsenic by DBDR were investigated. For trapping, arsenic could be completely trapped in DBDR at 40 mL/min of O2 input mixed with 600 mL/min Ar carrier gas and 9.2 kV discharge potential; prior to release, the Ar carrier gas input should be changed from the upstream gas liquid separator (GLS) to the downstream GLS and kept for 180 s to eliminate possible water vapor interference; for arsenic release, O2 was replaced by 200 mL/min H2 and discharge potential was adjusted to 9.5 kV. Under optimized conditions, arsenic could be detected as low as 1.0 ng/L with an 8-fold enrichment factor; the linearity of calibration reached R(2) > 0.995 in the 0.05 µg/L-5 µg/L range. The mean spiked recoveries for tap, river, lake, and seawater samples were 98% to 103%; and the measured values of the CRMs including GSB-Z50004-200431, GBW08605, and GBW(E)080390 were in good agreement with the certified values. These findings proved the feasibility of DBDR as an arsenic preconcentration tool for atomic spectrometric instrumentation and arsenic recycling in industrial waste gas discharge.