Solid electrolyte membranes face a huge challenge in achieving satisfactory interfacial contact with electrodes, which severely impairs the rate performance and cycle life of solid-state lithium ...batteries. In this work, we fabricated an ultrathin solid polymer electrolyte (SPE) membrane, and based on it we demonstrated the interfacial contact optimization strategy by in-situ polymerization. The free-stranding PVDF-HFP-LiTFSI membrane with a thickness of 20 μm shows an ionic conductivity of 1.2 × 10−4 S cm−1 at room temperature. The poly(ethylene glycol) diacrylate-based in-situ polymerized electrolyte tightly connects the cathode and the SPE membrane, decreasing the interfacial resistance from 9380 Ω cm2 to 1100 Ω cm2. Compared with the traditional method employing liquid electrolyte for interfacial wetting, extended electrochemical window (4.6 V) and much improved thermal stability are obtained. Full cell employing LiFePO4 cathode and lithium metal anode shows an initial capacity of 138.9 mAh g−1 under a charge/discharge rate of 0.5C (85 mA g−1) at 60 °C, with a capacity retention ratio of 84.9% and a high average Coulombic efficiency (98.7%) after 300 cycles, remarkably better than those of its liquid electrolyte-used counterpart. Our work demonstrates that the application of in-situ polymerization into interfacial contact improvement between SPE and cathode possesses wide application prospects.
•An ultrathin (∼20 μm) SPE membrane with high ionic conductivity is prepared.•SPE/cathode interfacial contact is remarkably improved by in-situ polymerization.•Li.|SPE|ISPE|LFP cell displays good cycling stability at high temperature (60 °C).
Analytical methods to quantify pesticide biomarkers in human population studies are critical for exposure assessment given the widespread use of pesticides for pest and weed control and their ...potential for affecting human health. We developed a method to quantify, in 0.2 mL of urine, concentrations of 10 pesticide biomarkers: four organophosphate insecticide metabolites (3,5,6-trichloro-2-pyridinol (TCPy), 2-isopropyl-6-methyl-4-pyrimidinol, para-nitrophenol, malathion dicarboxylic acid); five synthetic pyrethroid insecticide metabolites (4-fluoro-3-phenoxybenzoic acid, 3-phenoxybenzoic acid, cis and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCCA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid); and the herbicide 2,4-dichlorophenoxyacetic acid.
he method is based on enzymatic hydrolysis of conjugated urinary metabolites, extraction and pre-concentration of the deconjugated metabolites using automated online solid-phase extraction, and separation and quantification using liquid chromatography-isotope dilution tandem mass spectrometry.
Depending on the analyte, method detection limits were 0.1–0.6 ng/mL; mean accuracy, calculated as spike recoveries, was 91–102%, and total precision, given as percent variation coefficient, was 5.9–11.5%. Percent differences associated with three freeze-thaw cycles, 24-h benchtop storage, and short-term processed sample stability were <14%.
Method suitability was assessed by recurring successful participation in external quality assessment schemes and by analyzing samples from subjects with suspected exposure to pesticides (n = 40) or who self-reported consuming an organic diet (n = 50). Interquartile ranges were considerably lower for people consuming an organic diet than for those potentially exposed for cis-DCCA (0.37 ng/mL vs 0.75 ng/mL), trans-DCCA (0.88 ng/mL vs 1.78 ng/mL) and TCPy (1.81 ng/mL vs 2.48 ng/mL). This method requires one-fifth of the sample used in our previous method and is suitable for assessing background exposures to select pesticides in large human populations and for studies with limited sample volumes.
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•Novel LC-MS/MS method for quantifying pesticide biomarkers in urine•Online sample cleanup and isotope dilution LC-MS/MS pesticide exposure method•Method uses 0.2 mL urine and is sensitive, reproducible, and accurate•Suitable to assess background exposures in large-scale population studies
•SPE-gauge blending can significantly improve the drought monitoring utility of SPEs.•Impacts of different gauge densities on SPE-gauge blending are investigated.•Improvements of blending are ...different for different aspects in drought monitoring.•Medium gauge density is most ideal for SPE-gauge blending in drought monitoring.
Blending satellite-based precipitation estimation (SPE) data and in-situ gauge observation data can generate effective spatially-continuous-precipitation estimates with improved accuracy. This study assessed the improvement of the long-term SPE when blending with in-situ gauge observations for drought monitoring, using a simple but effective blending method named the geographical difference analysis (GDA) method and with the Precipitation Estimation from Remote Sensed Information by using Artificial Neural Networks-Climate Data Records (PERSIANN-CDR) as case study. In-situ precipitation observations from three meteorological station sets with different densities—the sparse (50), medium (200), dense (727) station set—were adopted to evaluate the effect of gauge density on the performance of SPE-gauge data blending. Two widely-used indices—standardized precipitation index (SPI) and self-calibrating Palmer drought severity index (SC_PDSI)—were used as case studies. Except the case of sparse 50-station subset, the SPE-gauge blending shows apparent improvement to the raw PERSIANN-CDR data, for both the accuracy of precipitation input and many aspects of drought monitoring, e.g. reproducing drought magnitude and revealing spatial pattern of drought, in which SC_PDSI shows more significant improvement than SPI. The dense 727-station set shows the largest improvement in the blending data, but the corresponding station-only interpolations also exhibit comparable performance to the blending data, indicating lower utilization value of the SPE data for these cases. Only the blending results of the medium-density 200-station set shows satisfactory drought monitoring performance as well as significant improvements relative to the station-only interpolations. According to the quantitative analyses, the medium density (about 50–75 gauges per 106km2 in our cases) might be the most economic gauge density for SPE-gauge blending, as it has satisfactory improvement in blending results, can make fullest use of the advantages of SPE data and requires relatively fewer gauges. Our results can help to understand how the SPE-gauge blending could improve the SPE-based drought monitoring and serves as a reference for applying drought monitoring under the data-limited conditions. Subsequent studies or applications should also carefully consider the effect of gauge density.
Solid-phase extraction (SPE) is the most widely used method for the extraction, changing of solvents, cleanup, concentration, and fractionation of organic compounds from a number of samples. This ...procedure is also very useful for desalting proteins and sugar samples. However, most SPE procedures are still poorly developed, with little consideration to the physics involved in the process and are described as largely empirical, labor-intensive, and time-consuming trial-and-error processes, without much systematization.
The objective of this study is to propose a number of contradictions, disagreements, failings, and shortcomings of the SPE procedures found elsewhere. The different arguments introduced in this study attempt to challenge the suitability of this procedure, particularly when it is conducted in the traditional manner (under gravity and at a high flow rate).
The first part of this study focuses on describing the state-of-the-art in SPE and its physical fundamentals.
This study provides the first pan-European reconnaissance of the occurrence of polar organic persistent pollutants in European ground water. In total, 164 individual ground-water samples from 23 ...European Countries were collected and analysed (among others) for 59 selected organic compounds, comprising pharmaceuticals, antibiotics, pesticides (and their transformation products), perfluorinated acids (PFAs), benzotriazoles, hormones, alkylphenolics (endocrine disrupters), Caffeine, Diethyltoluamide (DEET), and Triclosan. The most relevant compounds in terms of frequency of detection and maximum concentrations detected were DEET (84%; 454 ng/L), Caffeine (83%; 189 ng/L), PFOA (66%; 39 ng/L), Atrazine (56%; 253 ng/L), Desethylatrazine (55%; 487 ng/L), 1H-Benzotriazole (53%; 1032 ng/L), Methylbenzotriazole (52%; 516 ng/L), Desethylterbutylazine (49%; 266 ng/L), PFOS (48%, 135 ng/L), Simazine (43%; 127 ng/L), Carbamazepine (42%; 390 ng/L), nonylphenoxy acetic acid (NPE
1C) (42%; 11 μg/L), Bisphenol A (40%; 2.3 μg/L), PFHxS (35%; 19 ng/L), Terbutylazine (34%; 716 ng/L), Bentazone (32%; 11 μg/L), Propazine (32%; 25 ng/L), PFHpA (30%; 21 ng/L), 2,4-Dinitrophenol (29%; 122 ng/L), Diuron (29%; 279 ng/L), and Sulfamethoxazole (24%; 38 ng/L). The chemicals which were detected most frequently above the European ground water quality standard for pesticides of 0.1 μg/L were Chloridazon-desphenyl (26 samples), NPE
1C (20), Bisphenol A (12), Benzotriazole (8), N,N′-Dimethylsulfamid (DMS) (8), Desethylatrazine (6), Nonylphenol (6), Chloridazon-methyldesphenyl (6), Methylbenzotriazole (5), Carbamazepine (4), and Bentazone (4). However, only 1.7% of all single analytical measurements (in total ˜ 8000) were above this threshold value of 0.1 μg/L; 7.3% were > than 10 ng/L.
We report the use of a hyphenated HPLC-DAD(diode array detector)-HRMS/SPE NMR system for the separation and isolation of a complex mixture of esters, containing substances with very similar LC ...retention times. The literature known mono- and diesters of the drug Flurbiprofen and polyethylene glycol, which form a large number of substances with varying chain lengths, were chosen for this study. We demonstrate the use of this hyphenated system to quickly and effectively isolate sixteen of these highly similar individual esters in an automated fashion, demonstrating its applicability in standard pharmaceutical analysis and quality control of drugs. Both, synthetic solutions of these esters and extracts from Flurbiprofen lozenges were used for this purpose. By the sole use of this system, the individual compounds were isolated and UV, HRMS and 1D and 2D NMR data could be collected, enabling the identification and differentiation of the individual esters.
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•Broad application for standard pharmaceutical quality control.•Easy adaptation of standard HPLC methods used in pharmaceutical quality control.•Acquisition of all data required for the structural elucidation of pharmaceutical impurities in an automated fashion.•Easy separation of complex sample mixtures from medical products.
The sensitivity of complex analytical procedures depends not only on the sensitivity of the analytical instrument used, but also on the recovery degree of the examined analyte by the employed sample ...preparation method. The recovery degrees of individual cannabinoids reported in literature, estimated using the same sample preparation method, are unexpectedly divergent. Therefore, the aim of this study was a thorough assessment of the most commonly used sample preparation methods, such as protein precipitation, LLE, QuEChERS and SPE, in the context of the reliability of the obtained results. The presented report shows that the highest sensitivity, precision and reliability of the chromatographic analysis of CBG, CBD, ∆9-THC and CBN in human plasma can be obtained using SPE. The recovery degrees of these cannabinoids by SPE are highly repeatable and exceed 95 %, while they are significantly lower for such sample preparation methods as protein precipitation, LLE and QuEChERS (ca. 80, 65 and 87, respectively). Moreover, the supernatants obtained by the latter methods contain interferents evoking matrix-effect, which makes reliable quantification of the listed cannabinoids by GC difficult. To our knowledge, the paper is the first such extensive comparison of sample preparation procedures used for the determination of cannabinoids in plasma by GC-MS and HPLC-MS. The presented results and the discussion allow to understand why different recovery degrees for the same xenobiotic can be find in literature despite they have been estimated using the same or different sample preparation method or different chromatography types.
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•Analyte recovery degree as a key factor in analytical procedure of complex mixtures.•SPE gives almost 100 % recovery of cannabinoids from blood plasma.•SPE allows for reliable analysis of cannabinoids in blood/plasma by GC and HPLC.•Plasma LLE and QuEChERS supernatants contain interferents evoking matrix effect in GC.
A simplified sample preparation method in combination with gas chromatography–triple-quadrupole mass spectrometry (GC-MS/MS) analysis was developed and validated for the simultaneous determination of ...227 pesticides in green tea, ginseng, gingko leaves, saw palmetto, spearmint, and black pepper samples. The botanical samples were hydrated with water and extracted with acetonitrile, magnesium sulfate, and sodium chloride. The acetonitrile extract was cleaned up using solid phase extraction with carbon-coated alumina/primary–secondary amine with or without C18. Recovery studies using matrix blanks fortified with pesticides at concentrations of 10, 25, 100, and 500 μg/kg resulted in average recoveries of 70–99% and relative standard deviation of 5–13% for all tested botanicals except for black pepper, for which lower recoveries of fortified pesticides were observed. Matrix-matched standard calibration curves revealed good linearity (r 2 > 0.99) across a wide concentration range (1–1000 μg/L). Nine commercially available tea and 23 ginseng samples were analyzed using this method. Results revealed 36 pesticides were detected in the 9 tea samples at concentrations of 2–3500 μg/kg and 61 pesticides were detected in the 23 ginseng samples at concentrations of 1–12500 μg/kg.
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•Molecularly imprinted polymers (MIPs) synthesized using penconazole as template molecule and N-Isopropylacrylamide (NIPAM) as functional monomer show good recognition properties ...toward the triazole ring.•Widely employed triazole pesticides can be efficiently isolated from complex matrices (i.e. juices, surface water) by the strategy of dispersive solid phase extraction using the developed MIPs as selective sorbents (MIP-d-SPE).•Plackett-Burman design of experiment is a useful tool to screen the effect of different combinations of functional monomers and cross linkers as well as the effect of different extraction conditions.
In the present study, novel molecularly imprinted polymers were prepared using penconazole as template and different combinations of functional monomers (acrylic acid (AA) and N-isopropylacrylamide (NIPAM)) and cross-linkers (ethylene glycol dimethacrylate (EGDMA) and trimethylolpropane trimethacrylate (TRIM)), according to a Plackett-Burman design of experiments. Materials were fully characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and nitrogen adsorption analysis. Rebinding behaviors in solution were studied both at the equilibrium (Langmuir, Freundlich and Temkin models), and at the non-equilibrium (pseudo-first, pseudo-second order kinetics). Materials were further tested as sorbents for dispersive solid phase extraction (d-SPE) on apple juice for multicomponent recovery of triazole fungicides at trace level, testing several variations of extraction parameters (juice pH, amount of sorbent, adsorption time, desorption solvent, desorption time) leading to the selection of the best materials and simultaneously of the best extraction conditions. MIPs synthesized with NIPAM showed significatively higher affinity for triazole pesticides in apple juice than the ones synthesized with AA, while no differences emerged for the two cross-linkers employed (EGDMA, TRIM). Selectivity was also assessed, testing MIPs as d-SPE sorbents in undiluted apple juice spiked with triazole pesticides concurrently with other interfering compounds. The newly developed NIPAM-based penconazole-imprinted MIPs showed an excellent recognition mechanism towards compounds containing the triazole ring, and significatively lower recoveries for other compounds. The developed analytical procedure based on molecularly imprinted polymer dispersive solid phase extraction and liquid chromatography coupled with mass spectrometry (MIP-d-SPE-LC-MS) was validated for selective enrichment and determination of triazole compounds in apple juice samples and river water samples with good recoveries (94.67%–109.03% for river water, 89.79%–110.23%, for apple juice), high repeatability (RSD% < 3.97 for river water, RSD% < 4.85 for apple juice), and reproducibility (RSD% < 5.95 for river water and RSD% < 7.14 for apple juice).
In this study, solid-phase extraction (SPE) of the pesticides, including ametryn, prometon, bentazon, carbendazim, tebuconazole, dimethoate and their degradation products, deisopropylatrazine and ...hydroxyatrazine, with high-performance liquid chromatography-tandem mass spectrometric analysis, was reported. The SPE approach consisted of the application of hydrophilic lipophilic-balanced polymer (HLB), strong cation, and anionic exchange sorbents packed in layered sequence in a single cartridge. The influence of various parameters on the extraction process was investigated, including sample solution pH, elution solvent, ionic strength and sample loading volume. Under the optimal conditions, the relative recoveries of the analytes ranged from 76 to 97% for spiked water and surface water samples with relative standard deviations of 1–9%. The method displayed low method detection limits for both water matrices (0.001–41.27 ng L−1) and achieved good linearity over the tested range of concentrations. Sequential-mode SPE provided higher extraction efficiency for pesticides than liquid-liquid extraction, and the adsorption capacity was greater than that of commercial HLB material, in the presence of humic acids. Eleven reservoir water samples were processed by the procedure, and tebuconazole was detected in all samples at concentrations of between 0.12 and 15.93 ng L−1, confirming that this mode of SPE was suitable for application to real samples.
•A sequential-mode SPE cartridge was constructed to enrich pesticides and their degradation products in water.•Sample detection using sequential-mode SPE and LC-MS achieves recoveries ranging from 76–97%.•The method was applied to reservoir water samples with valid results.
