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On-site extraction plays a significant role in the reliable quantification of strong polar phenoxycarboxylic acid herbicides (PCAs) in aqueous samples. In current study, a new technique for the field sample preparation of PCAs was developed by means of three channels in-tip microextraction device (TCIM). To capture PCAs effectively, an extraction phase based on monolith (EPM) using vinylimidazole and divinylbenzene/ethylene dimethacrylate as monomer and cross-linkers, respectively, was in-situ synthesized in pipette tips. The EPM fabricated at optimal conditions were characterized by a series of techniques and employed as the adsorbent of TCIM for the on-site extraction of PCAs. The adsorption isotherm was studied so as to inspect the extraction behaviors of EPM towards PCAs. Results revealed that the proposed EPM/TCIM presented satisfactory extraction performance towards PCAs through multiple interactions. The enrichment factors and adsorption capacity were 74-277 and 20 mg g-1, respectively. Under the most beneficial extraction parameters, the developed EPM/TCIM was successfully employed to on-site extract PCAs, and then combining with HPLC equipped with diode array detector to monitor trace PCAs in actual waters. The limits of detection (LODs) towards investigated PCAs varied from 0.071 µg/L to 0.30 µg/L. In addition, the accuracy of established approach was inspected with documented method. Compared with existing lab-based sample preparation approaches, the introduced field sample preparation technique exhibits some merits such as avoidance of transporting large volume of water, prevention of analytes loss during sampling procedure, less usage of organic solvent and achievement of satisfactory efficient in sample preparation.

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Efficient extraction is a vital step in mercury speciation. In this context, using 4-vinylbenzeneboronic acid and 9-vinylanthracene as functional monomers, a new magnetic adsorbent was fabricated according to one-pot hydrothermal approach. Various characterization results prove the as-prepared adsorbent presented abundant functional groups and saturation magnetism. Combining with magnetic solid phase extraction (MSPE), the adsorbent exhibited satisfactory entrapment performance towards different mercury species which had been pre-coordinated with dithizone to form metal-organic coordination. A series of parameters influencing the extraction performance were inspected in detail. Under the most beneficial conditions, sensitive and reliable approach to quantify trace methylmercury, ethylmercury, phenylmercury and inorganic mercury in aqueous samples was developed by the combination of HPLC/DAD. Limits of detection and precision located in the ranges of 0.012-0.074 µg/L and 2.5-9.8%, respectively. Recoveries with low, medium and high fortified contents in actual waters varied from 79.8 to 119%. Confirmatory experiments were performed to evidence the accuracy and reliability of established approach. In addition, a possible mechanism was suggested based on the chemical nature of analytes, extraction conditions and characterization results.

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An efficient multiple fibers solid-phase microextraction method based on porous monolith was established for Se(IV) and Se(VI) analysis. Poly(4-vinylphenylboronic acid/styrene-co-ethylene dimethacrylate/divinylbenzene) monolith was fabricated and employed as the extraction phase for efficient entrapment of Se(IV) complexed with o-phenylenediamine, followed by elution with a methanol/formic acid (99/1.0, v/v) mixture and quantification by high-performance liquid chromatography with diode array detector. The Se(VI) species was measured by the difference between total inorganic Se and Se(IV) after pre-reduction. Different characterization techniques were employed to inspect the structure and morphology of prepared adsorbent. A series of key extraction factors were optimized so as to achieve the expected extraction performance. Under the optimized separation and capture parameters, the linear range and limit of detection for Se(IV) in water sample were 0.050-200 and 0.013 µg/L, respectively. For beer sample, the corresponding values were 0.010-300 and 0.032 µg/L. The developed microextraction approach was successfully utilized to detect trace Se(IV) and Se(VI) in environmental water and beer samples with satisfactory fortified recovery and repeatability. Results well reveal the attractive merits of the established method in the analysis of Se species, including simple preparation of adsorbent, convenient extraction procedure, good sensitivity, high cost-effectiveness, and eco-friendliness.

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Polyhalogenated carbazoles (PHCs) have been frequently detected in various environments and have gained increasing attention due to their dioxin-like toxicity. In this study, 28 surface sediments and three sediment cores were collected from the northern South China Sea (SCS) to investigate the spatial and temporal distribution trends of PHCs. The total concentrations of PHCs in the surface sediments ranged from 0.25 ng/g to 3.10 ng/g, with a median concentration of 1.50 ng/g. The composition profiles of PHCs in the surface sediments were dominated by 3,6-dichlorocarbazole (36-CCZ), 3,6-dibromocarbazole (36-BCZ), and 1,3,6,8-tetrabromocarbazole (1368-BCZ). The total organic carbon (TOC) based concentrations of 36-CCZ, 1-bromo-3,6-dichlorocarbazole, 1,3,6,8-tetrachlorocarbazole, and 1368-BCZ showed significant positive correlation with water depth (r = 0.58-0.88, p values < 0.01). On the contrary, the TOC based concentration of 2,3,6,7-tetrachlorocarbazole displayed a significant negative correlation with the water depth (r = -0.52, p < 0.01). However, no significant correlation was observed for 3-chlorocarbazole, 36-BCZ, and 1,3,6-tribromocarbazole (p values > 0.05). PHCs in sediment cores showed that congener profiles and concentrations of PHCs remained largely stable throughout the 1890s and 2010s. In addition, all the detected PHCs displayed a significant positive correlation with TOC content of the sediments. These unique spatial and temporal distribution patterns suggest that both terrigenous and natural marine sources contributed the observed PHCs in sediments of the northern SCS.

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Salinity has considerable effects on the toxicity of metals in estuarine waters. The effects of salinity are manifold, making it difficult to summarize for risk assessments. In this study, we separated and quantified the multiple effects of salinity on cadmium (Cd) in a toxicokinetic-toxicodynamic framework. The estuarine clam, Potamocorbula laevis, was used as a model organism. Cd bioaccumulation was measured using a stable-isotope-tracer technique; in parallel, toxicity tests were conducted. With the increase of salinity from 5 to 30, Cd uptake decreased monotonically. In contrast, the intrinsic sensitivity of organisms, measured by the toxicodynamic parameters, reached its minimum at intermediate salinities (i.e., 10 to 20). The overall salinity effects were dominated by the effects on Cd bioaccumulation; therefore, Cd toxicity decreased monotonically with the increases of salinity. The model developed in this study could provide predictions of no-effect concentration (1.7 to 34.9 µg L-1, end point mortality) and the median lethal concentration (LC50) of Cd at different salinities. In conclusion, we developed a framework for quantifying the multiple effects of salinity and a method for estimating no-effect concentration from acute toxicity tests, which can be used for better assessments of metal risks in estuarine waters.

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A quick and sensitive method was developed for the trace determination of Cd(II), Pb(II) and Cu(II) ions in water and bean samples. It is based on a combination of magnetic solid phase extraction (MSPE) and graphite furnace atomic absorption spectrometry (GFAAS). Allylthiourea (which contains abundant sulfur and nitrogen atoms) was copolymerized with ethylene dimethacrylate on the surface of magnetite (Fe3O4) nanoparticles to prepare a new adsorbent for use in MSPE. Various technologies were used to characterize the morphology, spectroscopic and magnetic properties of the adsorbent, and several parameters that affect the extraction performance were optimized. The adsorbent can enrich Cd(II), Pb(II) and Cu(II) ions via chelation interaction. Following elution with 0.1 mol·L-1 HNO3, the ions were quantified by GFAAS. Under the most favorable conditions, the limits of detection are from 3.3-7.2 ng·L-1 for water samples, and 1.1-1.5 µg·kg-1 for beans. The method displays wide linear analytical ranges and good precision. It was successfully applied to the determination of the metal ions in water and bean samples. The recoveries from spiked samples ranged between 80.5 and 114% in water, and from 82.2 to 118% in bean samples. The relative standard deviations of reproducibility were < 10%. Graphical abstract Schematic presentation of the magetic solid phase extraction (MSPE) for the analysis of Cd(II), Pb(II) and Cu(II). MNP: magnetic nanoparticles; ATED: allylthiourea ethylene dimethacrylate copolymer.

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In this work, magnetic carbon material derived from pomelo peels (MCMPs) was conveniently fabricated utilizing one-pot synthesis method and employed as adsorbent of magnetic solid-phase extraction (MSPE). Several characterized measures including infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and vibrating sample magnetometer were used to investigate the morphology, spectroscopic and magnetic properties of prepared adsorbent. Apolar parabens and polar fluoroquinolones (FQs) were used to investigate the extraction performance of MCMPs. Under the optimized extraction conditions, the MCMPs displayed satisfactory extraction performance for target analytes. At the same time, the MCMPs/MSPE was combined with HPLC-DAD for the sensitive determination of parabens and FQs in real-life water samples. Results showed that the limits of detection (S/N = 3) for parabens and FQs were in the ranges of 0.011-0.053 µg/L and 0.012-0.46 µg/L, respectively. The spiked recoveries were in the range of 76.6-116% for parabens and 80.2-114% for FQs with good repeatability (relative standard deviations less than 10%). In comparison to reported methods, the developed MCMPs/MSPE-HPLC-DAD showed some merits including low-cost, simplicity, satisfactory sensitivity and green non-pollution.

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Two novel heterocyclic third components, hexahydropyridine (HHP) and 1-ethylpiperidine (EP) were firstly found to enhance room temperature phosphorescence (RTP) of alpha-bromonaphthalene (alpha-BrN) induced by cyclodextrin. The effects of equilibrium time for formation of inclusion complex, temperature, pH values and the variation of concentrations of each component on RTP of alpha-BrN and the RTP lifetime of each ternary complex had been investigated and compared to discuss inclusion mechanism of ternary complexes. The RTP lifetimes of alpha-BrN/beta-CD/HHP, alpha-BrN/beta-CD/cyclohexane (CH) and alpha-BrN/beta-CD/EP were 6.18, 7.71 and 9.36 ms, respectively. Based on the strongest RTP of alpha-BrN induced by CD in the presence of EP, a method for determination of EP was established. Under the optimal conditions, the analytical curve of EP gave a liner dynamic range of 1.50x10(-4) to 1.50x10(-3) mol L(-1) with a detection limit of 4.8x10(-5) mol L(-1). When the established CD-RTP method was applied to determine the concentration of EP synthetic samples in distilled water, the experimental results demonstrated that the recovery was 91.4% with a relative standard deviation less than 2.85% (n=7).

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