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The current non-chromatographic speciation methods generally involve the conversion of different species by oxidation/reduction reactions, which may cause inherent problems such as contamination risk, time consumption and complex operations. In this work, in-syringe solid phase extraction (IS-SPE) was combined with in-syringe vortex-assisted solidified floating organic drop microextraction (IS-VA-SFODME) for the detection of Sb(V) and Sb(III) in rice wines by graphite furnace atomic absorption spectrometry. Firstly, IS-SPE involved the use of ZnFe

In this work, magnetic dispersive micro-solid phase extraction (MDMSPE) coupled with dispersive liquid-liquid microextraction (DLLME) was developed for Se(IV) and Se(VI) followed by graphite furnace atomic absorption spectrometry. MDMSPE involved the use of magnetic ZnFe

Targeted high-throughput screening of inhibitors from natural products is an effective approach in the treatment of cancer progression. RhoA protein is essential for many signaling pathways. It is closely related to the occurrence and development of tumor. So far, there are only a few reports on the screening of small molecule inhibitors of RhoA protein from natural products. In this study, an online UHPLC-PDA-MS

In this study, for the first time, a novel separation and preconcentration method of direct immersion dual-drop microextraction (DIDDME) was proposed for the species of inorganic chromium (Cr(III) and Cr(VI)) followed by graphite furnace atomic absorption spectrometry detection. The methodology is based on that two organic drops hold on the needle tips of microsyringes were concurrently immersed in a stirred sample solution. Each drop contains a chelating reagent, which can react with a specific species under the same pH value. Therefore, Cr(III) and Cr(VI) can be selectively extracted into different drops. This procedure did not require tedious and complicated pre-oxidation/pre-reduction and centrifugation/filtration operations, which may lead to the risk of sample contamination and analysis errors. Main parameters influencing separation, preconcentration and identification of the target species were investigated. An enrichment factor of 400-fold was obtained for Cr(III) and Cr(VI). Under the optimized conditions, detection limits for this method were 1.1 ng L

Background Chromium is an interesting element because its toxicity depends on its speciation. Thus, knowledge of Cr speciation in cow milk is essential to human health. Objective This study aims to achieve real bioaccessible species in cow milk, including Cr(III), Cr(VI), residual, digestible, and total Cr. Methods Samples were treated with artificial gastric juice, followed by dispersive micro-solid phase extraction (DMSPE) combined with ICP-MS for Cr speciation. Fibrous g-C3N4@TiO2 nanocomposites (FGCTNCs) were used as a novel adsorbent for DMSPE. Results The method detection limits were 110 pg/g (Cr(III)) and 260 pg/g (Cr(VI)) for milk powder (0.1 g), and 5.1 pg/g (Cr(III)) and 13 pg/g (Cr(VI)) for liquid cow milk (2 mL). The relative standard deviations (RSDs), obtained by analyzing the standard solutions containing 1.0 ng/mL of the analytes in sequence for nine times, were 4.3% and 5.1% for Cr(III) and Cr(VI), respectively. Linearity was observed over the range of 4 magnitude orders with correlation coefficients better than 0.9961. The enrichment factor of 100 was obtained. The majority of Cr in the samples was transferred into digestion solution. The content of Cr(III) is much higher than that of Cr(VI) in the digestion solution. Conclusions This method has the advantages of reduced solvent consumption, less adsorbent dosage, and high extraction efficiency. It may become a valuable strategy for elemental species in food samples. Highlights The samples were treated with artificial gastric juice to avoid the inter-conversion of species. FGCTNCs exhibit the merits of N-rich functional groups and selective adsorption for the analytes.

In this work, fibrous TiO2@g-C3N4 nanocomposites (FTGCNCs) were used as a new adsorbent of dispersive micro-solid phase extraction for speciation of antimony in cow milk, including Sb(III), Sb(V), residual, digestible, and total Sb. Samples were prepared with artificial gastric juice to achieve bioaccessible species of elements before ICP-MS determination. Besides, adsorption behaviors of Sb(III) and Sb(V) on FTGCNCs were investigated. The results showed that Sb(III) was quantitatively adsorbed on FTGCNCs in the pH range of 2.0–4.0, while Sb(V) remained in aqueous phase. Sb(III) adsorbed on FTGCNCs was eluted completely with 1.5 mol L−1 HNO3 solution. The assay of Sb(V) was based on subtracting Sb(III) from total Sb. Total Sb was extracted and determined after the reduction of Sb(V) into Sb(III). The main parameters affecting the separation and determination of the analytes were examined in detail. Under optimal conditions, the limit of detection was 0.37 pg mL−1 for Sb(III) with relative standard deviation of 4.1% (c = 1.0 ng mL−1, n = 9). This method was successfully used for the analysis of Sb speciation in cow milk. To validate this method, a certified reference material of milk powder was analyzed, and the determined values were in good agreement with the certified values.

Non-chromatographic speciation methods generally involve speciation conversion, which may cause sample contamination, analysis errors and tedious operations. In this work, a direct immersion dual-drop microextraction (DIDDME) was firstly developed for separation and preconcentration of Cr(III) and Cr(VI). In DIDDME, two organic drops on needle tips of microsyringes were concurrently immersed in a stirred sample solution. Each drop contains a chelating reagent for reacting with a specific species. Thus, Cr(III) and Cr(VI) were selectively extracted into different drops. This method afforded detection limits of 3.0 and 4.1 ng/L, quantification limitof 10 ng/L and 14 ng/L, linear range of 0.01-30 ng mL

High-throughput screening of inhibitors from natural products is an efficient approach to target key enzymes in diabetes progression. In this study, an on-line detection system was established for the first time to rapidly screen inhibitors of α-amylase and α-glucosidase from Prunus mume. Among 28 identified compounds, 26 and 21 compounds showed strong inhibitory effect against α-amylase and α-glucosidase, respectively. Their inhibitory effects were validated by in vitro enzyme assay and fluorescence quenching which demonstrated that these inhibitors effectively interfered enzyme active sites. The inhibition kinetics suggested that chemical structures are of great importance for interfering the enzyme structures and their microenvironment polarity. Among evaluated compounds, isorhamnetin-3-O-glucoside (19) showed the strongest binding activities to α-amylase and α-glucosidase (6.34×10

Shuxuening injection (SXNI), one of the traditional Chinese medicine injections (TCMI), is widely used for the treatment of cardiovascular diseases in the clinic. However, its allergic reactions have impeded the clinical applications of SXNI, such adverse reactions have not been well understood due to the lack of methods for detecting haptens. In this study, a high-performance liquid chromatography-diode–array detector–multi-stage mass spectrometry–human serum albumin–fluorescence detector (HPLC–DAD–MSn–HSA–FLD) system was established to identify and screen haptens for the first time. Flavones, flavonols and their glycosides in SXNI showed strong HSA binding ability in different degrees. Fifteen of these compounds were used to study the association of HSA binding ability and sensitizability using isothermal titration calorimetry (ITC) and fluorescence techniques, furthermore, RBL-2H3 cell experiments were conducted to verify the results. It was found that ginkgolides showed no sensitizability, while flavones and flavonol aglycones showed stronger sensitizability than their glycosides. The system was proven to be precise, stable and reproducible, which lays a foundation for screening haptens in SXNI and relevant samples.

In this work, magnetic ZnFe2O4 nanotubes (ZFONTs) were synthesized, characterized and used as adsorbent for dispersive micro-solid phase extraction of Co(II), Ni(II), Mn(II) and Cd(II) before their determination by inductively coupled plasma mass spectrometry. Adsorption behaviors of target ions on ZFONTs were investigated. The results showed that the analytes were quantitatively retained on ZFONTs in the pH range of 6.0–8.0, and eluted completely with 1.0 mL of 0.4 mol L−1 HNO3. The separation of sorbent from aqueous phase was performed by an external magnet to avoid tedious centrifugation or filtration steps. Main parameters affecting preconcentration and determination of the analytes were studied in detail. Under optimum conditions, detection limits for Co(II), Ni(II), Mn(II) and Cd(II) were 0.10, 1.2, 3.7 and 0.09 pg mL−1, respectively. Relative standard deviations were

Proton exchange membrane (PEM) fuel cell is a promising renewable energy conversion technology due to its many unique advantages. Among its multiple components, flow field plays an important role in distributing reactants from flow channels to electrochemical reaction sites in catalyst layers (CL).Furthermore, since the reactions only occur at the triple-phase boundary regions where electrons, protons and reactants meet, the transport of oxygen affects the electrochemical active area (ECA) available for reaction. Interdigitated flow fields have been shown to be very effective in transporting reactants to the reaction sites in the CL. In this work, interdigitated flow fields with different outlet channel widths are employed to examine their effects on the cell performance and ECA. Experimental results show that with narrower outlet channels both the ECA and the cell performance increase significantly, at the expense of slight increase in the ohmic resistance.

As an extremely important component, flow field plays an important role in a proton exchange membrane (PEM) fuel cell. In this study, a two-dimensional model of interdigitated flow field was developed to simulate the effect of outlet channel width on PEM fuel cell performance using COMSOL Multiphysics, and the simulated results coincided accurately with the experimental results. From the results, the PEM fuel cell performance with narrower outlet channel width was better than that with conventional outlet channel width, since the molarity distribution of oxygen in the porous medium and the electrolyte current density distribution at the membrane cross section were more uniform, and the drainage capacity was stronger. The simulated results have certain reference significance for the design and optimization of interdigitated flow field.

Four new honokiol derivatives, namely 8′,9′-dihydroxymagnaldehyde E (1), 8′,9′-dihydroxyhonokiol (2), erythro-7-O-methylhonokitriol (3), and threo-7-O-methylhonokitriol (4), together with seven known compounds, erythro-honokitriol (5), threo-honokitriol (6), magnaldehyde E (7), magnotriol B (8), magnaldehyde B (9), honokiol (10), and magnolol (11), were isolated from the stem bark of Magnolia officinalis. Their structures were established on the basis of extensive 1D and 2D NMR experiments as well as HR-MS. All isolates were evaluated for their in vitro activities against acetylcholinesterase and butyrylcholinesterase, the results demonstrated that compound 8 possessed potent inhibitory activity.

Establishing exploration vectors to infer the properties of ore-forming fluids, locate blind ore bodies with the aid of visible to near-infrared (VNIR) and short-wave infrared (SWIR) spectroscopy, and infer the chemistry of minerals, is a new research interest for economic geology. Common alterations and clay minerals, including sericite, chlorite, epidote, alunite, kaolinite, tourmaline, etc., are ideal objects for the study of exploration indicators due to their sensitivity to variations in the nature of hydrothermal fluid. The diagnostic spectral feature and chemistry vary spatially and systematically with physicochemical change. VNIR spectroscopy can characterize the REE-bearing clay minerals directly. Obtaining spectral or chemical parameters with the aid of VNIR-SWIR spectroscopy, electron probe micro-analyzer (EPMA) or laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) can help to establish exploration vectors. This paper systematically summarizes recent advances in mineral exploration indicators (MEIs) of VNIR-SWIR spectroscopy and chemistry, and compares them in different regions or deposits. We found that some MEI spatial variation trends are random, even the same type of deposit can show an opposite trend. The controlling factors that limit the application of the established MEIs are vague. Conducting further research on petrology and mineralogy with the aids of observation under microscopy, X-ray diffraction (XRD), TESCAN Integrated Mineral Analyzer (TIMA), and EPMA are suggested to discover alteration mineral assemblage, alteration stages, and behaviors of “the pathfinder elements” related to mineralization. Based on the above research, the physicochemical properties of ore-forming fluids and their control over MEIs can be inferred. Refining the theoretical basis is critical to understanding and popularization of spectral and chemical MEIs.

Magnetic dispersive microsolid phase extraction (MDMSPE) was coupled with dispersive liquid���liquid microextraction (DLLME) for the separation and preconcentration of arsenic(V) and arsenic(III) prior to graphite furnace atomic absorption spectrometry detection. In the first step, magnetic ZnFe2O4 nanotubes were employed for adsorbing arsenic(V). The adsorbent was separated from the aqueous phase by the use of an external magnetic field. Next, arsenic(III) in the upper aqueous phase from MDMSPE was enriched by DLLME. Samples were prepared with artificial gastric juice to avoid inter-conversion of the determined species. The parameters affecting the separation and preconcentration of the determined species were optimized. The detection limits of this protocol were determined to be 1.3 and 2.0 pg mL���1 for arsenic(III) and arsenic(V) with relative standard deviations of 4.5% and 5.6% for a concentration of 1.0 ng mL���1 (n = 9). The enrichment factors were equal to 175-fold for arsenic(III) and 163-fold for arsenic(V). The developed protocol was employed for the determination of arsenic(III) and arsenic(V) in dairy products without preoxidation or prereduction. The recoveries of spiked samples were from 90.8% to 105%. A milk powder certified reference material was analyzed by this approach and the measured results were in good agreement with the certified value.