Validation of an LC-MS/MS method for the quantitative determination of a novel fungicide: pyraoxystrobin in rat plasma and its application to a toxicokinetics study

A simple, sensitive, and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for determination of pyraoxystrobin in rat plasma and applied to a toxicokinetics study. The separation was performed by gradient elution on a Luna 5 μ C18 (2) 100 Å column (50?×?4.6 mm I.D., 5 μm) with mobile phase: water (0.1 % formic acid, v/v)/acetonitrile (0.1 % formic acid, v/v), followed by quantification with a mass detector in multiple reaction monitoring (MRM) mode using ESI as an interface. The calibration curve was linear over a concentration range of 1.00–200 ng/mL. The recovery for pyraoxystrobin ranged from 101.4 to 108.2 %. The intraday bias and precision ranged from ?9.3 to 8.1 % and from 0.7 to 8.4 %, respectively, and the interday bias and precision ranged from ?0.3 to 4.0 % and from 4.4 to 7.2 %, respectively. The toxicokinetics of pyraoxystrobin after single 100 and 1,000 mg/kg oral doses were studied in rats. Figure

The chromatogram of pyraoxystrobin highest calibration standard (ULOQ) extract.     

Reliable screening of pesticide residues in maternal and umbilical cord sera by gas chromatography-quadrupole time of flight mass spectrometry

The widespread use of pesticides induces heavy adverse effects on human health,especially for the pregnant women and the newborns.In this study,a screening method has been developed for the determination of multi-pesticides in maternal and umbilical cord sera.All pesticides in sera were collected using solid phase extraction(SPE),and analyzed by gas chromatography-quadrupole time of flight mass spectrometry(GC-QTOF MS).To set up the quality criteria,a database of 50 pesticides was created and the accurate masses of 3 up to 5 representative ions with their intensity ratios were included for each pesticide.In addition,a novel"identification points"(IPs)system relying on the accurate MS1 and MS2 spectra was used to interpret the data for each suspected pesticide.The methodology was then applied to a pair of maternal and umbilical cord sera.A total of six pesticide residues were screened out successfully.In conclusion,GC-QTOF MS combined with an accurate mass database seemed to be one of the most efficient tools for systematic pesticide analysis.     

PPh3‐Catalyzed Ring‐Expansion Reactions of Sulfamate‐Derived Cyclic Imines with Acetylenedicarboxylates

The PPh₃‐catalyzed ring‐expansion reaction of sulfamate‐derived cyclic imines with acetylenedicarboxylates has been developed. The reaction works quite efficiently under very mild conditions to afford benzo[g][1,2,3]oxathiazocine‐4,5‐dicarboxylate 2,2‐dioxide derivatives in high yields.     

Stable Encapsulation of Acrylate Esters in Networked Molecular Capsules

Reactive acrylate esters were encapsulated in the cavity of networked molecular capsules in a single‐crystal‐to‐single‐crystal fashion. Owing to the encapsulation effect, acrylates inside the capsules do not undergo polymerization upon irradiation with UV light or heating, while the guest molecules can be quantitatively extracted by treatment with toluene.     

Counter‐anion role in the formation of two supramolecular complexes: [Ag2(DPP)2](ClO4)2·CH3CN and [Ag2(DPP)2(NO3)2] {DPP is N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine}

The title compounds, bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ²N¹:P}disilver bis(perchlorate) acetonitrile monosolvate, [Ag₂(C₁₈H₁₇N₂P)₂](ClO₄)₂·CH₃CN, (1), and bis{μ‐N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine‐κ²N¹:P}bis[(nitrato‐κ²O,O)silver], [Ag₂(C₁₈H₁₇N₂P)₂(NO₃)₂], (2), each contain disilver macrocyclic [Ag₂(C₁₈H₁₇N₂P)₂]²⁺ cations lying about inversion centres. The cations are constructed by two N‐[(diphenylphosphanyl)methyl]pyridin‐4‐amine (DPP) ligands linking two Ag⁺ cations in a head‐to‐tail fashion. In (1), the unique Ag⁺ cation has a near‐linear coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands. Two ClO₄⁻ anions doubly bridge two metallomacrocycles through Ag...O and N—H...O weak interactions to form a chain extending in the c direction. The half‐occupancy acetonitrile molecule lies with its methyl C atom on a twofold axis and makes a weak N...Ag contact. In (2), there are two independent [Ag(C₁₈H₁₇N₂P)]⁺ cations. The nitrate anions weakly chelate to each Ag⁺ cation, leading to each Ag⁺ cation having a distorted tetrahedral coordination geometry consisting of one pyridine N atom and one P atom from two different DPP ligands, and two chelating nitrate O atoms. Each dinuclear [Ag₂(C₁₈H₁₇N₂P)₂(NO₃)₂] molecule acts as a four‐node to bridge four adjacent equivalent molecules through N—H...O interactions, forming a two‐dimensional sheet parallel to the bc plane. Each sheet contains dinuclear molecules involving just Ag1 or Ag2 and these two types of sheet are stacked in an alternating fashion. The sheets containing Ag1 all lie near x = , , etc, while those containing Ag2 all lie near x = 0, 1, 2 etc. Thus, the two independent sheets are arranged in an alternating sequence at x = 0, , 1, etc. These two different supramolecular structures result from the different geometric conformations of the templating anions which direct the self‐assembly of the cations and anions.     

Thermoresponsive AuNPs Stabilized by Pillararene‐Containing Polymers

Pillararene‐containing thermoresponsive polymers are synthesized via reversible addition–fragmentation chain transfer polymerization using pillararene derivatives as the effective chain transfer agents for the first time. These polymers can self‐assemble into micelles and form vesicles after guest molecules are added. Furthermore, such functional polymers can be further applied to prepare hybrid gold nanoparticles, which integrate the thermoresponsivity of polymers and molecular recognition of pillararenes.

     

A novel 3D Tesla valve micromixer for efficient mixing and chitosan nanoparticle production

Current three-dimensional micromixers for continuous flow reactions and nanoparticle synthesis are complex in structure and difficult to fabricate. This paper investigates the design, fabrication, and characterization of a novel micromixer that uses a simple spatial Tesla valve design to achieve efficient mixing of multiple solutions. The flow characteristics and mixing efficiencies of our Tesla valve micromixer are investigated using a combination of numerical simulations and experiments. The results show that in a wide range of flow rates, viscoelastic solutions with different concentrations can be well mixed in our micromixer. Finally, experiments on the synthesis of chitosan nanoparticles are conducted to verify the practicability of our micromixer. Compared with nanoparticles prepared by conventional magnetic stirring, the size of nanoparticles prepared by micromixing is smaller and the distribution is more uniform. Therefore, our Tesla valve micromixer has significant advantages and implications for mixing chemical and biological reactions.     

Synthesis and Chromatographic Evaluation of Perfluorooctyl Stationary Phase for Separation of Basic Compounds

Fluorinated stationary phases provide unique separation effect on basic compounds, due to the fluorine atoms, and pentafluorophenyl stationary phases (PFPs) are the most widely used. Considering that some fluoroalkyls have higher fluorine contents than PFPs do, it is speculated that fluoroalkyl stationary phases should have potential new applications. Herein, we synthesized a silica-based stationary phase bonding perfluoroctyl (FC8) proved by characterization through elemental analysis and solid-state ¹³C cross-polarization/magic-anglespinning nuclear magnetic resonance. The chromatographic behavior of the stationary phase was evaluated with test compounds. In addition, to further study the applicability of FC8 materials, Corydalis decumbens (Thunb.) Pers. fraction, considered as a challenging medicine on reversed-phase chromatography columns, was chosen as a test sample. Results demonstrated that the FC8 stationary phase had better and more satisfactory separation performance than the PFP stationary phase on basic compounds.

     

Surface and Interface Engineering for Advanced Nanofiltration Membranes

Nanofiltration has been attracting great attention in alleviating the global water crisis because of its high efficiency,mild operation,and strong adaptability.Over decades,it remains a challenge to break the upper limit of performance and establish the formation-structureproperty relationship for nanofiltration membranes.This feature article summarizes our recent progress in the preparation of high-performance thin-film composite(TFC)nanofiltration membranes,focusing on the mussel-inspired deposition method and the optimized interfacial polymerization(IP).By accelerating the oxidation of polydopamine and equilibrating the rate of aggregation and deposition processes,the mussel-inspired deposition method realizes the rapid and uniform formation of selective coatings or nanofilms.Diverse deposition systems endow the selective layer with rich chemical structures and easy post-functionalization,highlighting its potential in water treatment.As for optimizing the conventional IP,the rapid polycondensation of amine and acid chloride groups is slowed down to enable the controllability of IP at the water-organic interface.The homogeneity and integrity of the TFC membranes are improved by constructing a uniform reaction platform and introducing a viscous medium to control the amine diffusion,which facilitates the water permeability and promotes the separation efficiency.We have proposed a series of practical strategies for improving TFC membranes and might provide more inspiration for other nanofiltration techniques.