Rapid screening and determination of nerve agent metabolites in human urine by LC-MS/MS

Qualitative screening procedures have been developed for the rapid detection and identification of the metabolites of nerve agents in the urine samples and extracts using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The combination of negative electrospray ionization (ESI) using a C₁₈ column and water-methanol mobile phase modified with ammonium formate provides a rapid screening procedure for nerve agent degradation products with limit of detection of 1 ng/mL in the precursor-ion analysis. Also, determination of the alkyl methylphosphonic acids was carried out by the SRM scan mode with the limit of detection of 0.1 ng/mL. These procedures will be applicable to the trace analysis of metabolites of nerve agents in human urine matrices in the Organisation for the Prohibition of Chemical Weapons (OPCW) proficiency test.     

Ca8Mg（SiO4）4Cl2∶Eu2+,Ce3+,Mn2+绿色荧光粉发光性能及其应用研究

利用高温固相法,合成出Eu2+、Ce3+、Mn2+共掺的Ca8Mg(SiO4)4Cl2系列绿色荧光粉。通过XRD表征了这些荧光粉的结构,通过分子荧光光谱仪研究了它们的室温发光性能。首先调查了Eu2+掺杂的Ca8Mg(SiO4)4Cl2绿色荧光粉发光性能,随后引入Ce3+、Mn2+提高了Ca8Mg(SiO4)4Cl2∶Eu2+在紫外光区的吸收强度及绿光发射强度。最后将筛选出来的荧光粉与InGaN-LED芯片组装制作成单一绿光LED器件,利用Ca7.8215MgSi4O16Cl2∶0.0525Eu2+,0.056Ce3+,0.070Mn2+所制作成的绿光LED器件发光最强,在20mA电流激发下,此LED发很强的绿光,其电致发光光谱所对应的色坐标值为:x=0.26,y=0.55。     

Physical and electrochemical properties of (La0.3Sr0.7)0.93TiO3–δ synthesized by Pechini method as an anode material for solid oxide fuel cells

The lanthanum strontium titanate (LST) has to be calcined at significantly high temperature (above 1,300 °C) to obtain its pure perovskite structure when synthesized by conventional solid-state method, which is main reason for reducing active surface area. In this study, A-site deficient (La_0.3Sr_0.7)_0.93TiO₃ was synthesized by Pechini method. Although the prepared powders were calcined at 600 °C, the pure perovskite structure can be obtained without any secondary phase such as TiO₂. Moreover, the porosity and surface area are 6 times and one order of magnitude higher in the LST powders synthesized by Pechini method than in the powders synthesized by solid-state method. Based on these results, the LST electrode (Pechini) leads to two times lower electrode resistance than the LST electrode (solid-state). Thus, the LST powders synthesized by Pechini can contributes to saving the energy needed for calcination process as well as increasing the porosity and active surface area, enhancing physical and electrochemical properties in SOFC anode.     

Synthesis and self-assembly behavior of thermoresponsive poly(oligo(ethylene glycol) methyl ether methacrylate)-POSS with tunable lower critical solution temperature

This article reports on the synthesis of a novel amphiphilic polyhedral oligomeric silsesquioxane (POSS) end-capped poly(2-(2-methoxyethoxy)ethyl methacrylate)-co-oligo(ethylene glycol) methacrylate) (POSS-P(MEO₂MA-co-OEGMA)). These thermoresponsive organic–inorganic hybrid polymers exhibit critical phase transition temperature in water, which can be finely tuned by changing the feed ratio of OEGMA and MEO₂MA. The lower critical solution temperature (LCST) of POSS-P(MEO₂MA-co-OEGMA) increases from 31 to 59 °C with the increasing of OEGMA content. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) studies show that these polymers can self-assemble into spherical micelles with the thermosensitive block into the corona and the POSS forming the core, and larger aggregates are formed when the temperature values are above their LCSTs. These thermoresponsive polymers POSS-P(MEO₂MA-co-OEGMA) with self-assembly behavior and tunable tempetature-responsive property have the potential applications in material science and biotechnology.     

Synthesis and structure of novel 6-(pyrazol-1-yl)-4-methyl-1H-pyrazolo[3,4-b]pyridin-3-ol derivatives

New 6-(pyrazol-1-yl)pyrazolo[3,4-b]pyridin-3-ol compounds were synthesized by cyclization reaction from 2,6-dichloro-4-methylnicotinonitrile. Their derivatives exist as the 3-hydroxy tautomer. The structure of the compound 1a of one of the resulting compounds was studied in detail by X-ray diffraction.     

Research on gamma-ray irradiation-assisted synthesis of cross-linked polystyrene via bulk polymerization

Journal of Radioanalytical and Nuclear Chemistry - Controlling heat accumulation is one of the major challenges for block materials synthesizing via bulk polymerization. In the paper, cross-linked...     

Quantification of imatinib and related compounds using capillary electrophoresis-tandem mass spectrometry with field-amplified sample stacking

A quantification method for imatinib (IM), its major metabolite N-desmethyl imatinib (NDI), and a degradation by-product was developed using CE–MS combined with an online concentration technique. The use of multiple reaction monitoring (MRM)–MS/MS further improved the sensitivity of this technology. Liquid–liquid extraction (LLE) using tertiary butyl methyl ether yielded high recovery and reproducibility for the pretreatment of serum samples. The recovery rate exceeded 83% for all three analytes, and was 90% for IM. To improve quantification results, a conductivity-induced online analyte concentration technique, field-amplified sample stacking (FASS), was used. The S/N ratios were improved at least 10-fold when compared with conventional capillary zone electrophoresis. The detection limits were 0.2 ng/mL for IM, 0.4 ng/mL for NDI, and 4 ng/mL for the degradation by-product. These results are superior to those previously obtained by other reported methods. The new method was validated in terms of its selectivity, intra- and interday repeatability and accuracy, and sample storage stability, following the guidelines issued by the European Medicines Agency. Considering the convenient pretreatment procedure (LLE), superior sensitivity, and fast analysis speed (<15 min), this method can be useful in the determination of imatinib levels in blood.     

Switchable Polymerization Triggered by Fast and Quantitative Insertion of Carbon Monoxide into Cobalt–Oxygen Bonds

A strategy that uses carbon monoxide (CO) as a molecular trigger to switch the polymerization mechanism of a cobalt Salen complex [salen=(R,R)-N,N′-bis(3,5-di-tert-butylsalicylidene)-1,2-cyclohexanediamine] from ring-opening copolymerization (ROCOP) of epoxides/anhydrides to organometallic mediated controlled radical polymerization (OMRP) of acrylates is described. The key phenomenon is a rapid and quantitative insertion of CO into the Co−O bond, allowing for in situ transformation of the ROCOP active species (Salen)Co^III-OR into the OMRP photoinitiator (Salen)Co^III-CO₂R. The proposed mechanism, which involves CO coordination to (Salen)Co^III-OR and subsequent intramolecular rearrangement via migratory insertion has been rationalized by DFT calculations. Regulated by both CO and visible light, on-demand sequence control can be achieved for the one-pot synthesis of polyester-b-polyacrylate diblock copolymers (Đ<1.15).     

Hierarchical self-assembly of 3D amphiphilic discrete organoplatinum(Ⅱ)metallacage in water

Here we described the design and synthesis of a discrete 3D amphiphilic metallacage 4,in which the tetragonal prismatic frameworks act as the hydrophobic cores and the poly(ethylene glycol)(PEG)chains as the hydrophilic tails.The structure of 4 was characterized by 1H NMR,31P NMR and electrospray ionization time-of-flight mass spectrometry(ESI-TOF-MS).Notably,4 with its Iong PEG tails was subsequently ordered into micelles at a low concentration(1.20×10^-6 mol/L)in water.As the concentration and cultivation time increased,the micelles can further self-assembly into nanofibers and nanoribbons.Considering the dynamic property of the coordination bond,these structures show reversible transformation under external stimuli.     

Thermal hazard assessment and ranking for organic peroxides using quantitative structure–property relationship approaches

Journal of Thermal Analysis and Calorimetry - Chemical reactivity hazards of organic peroxides are major concerns of the chemical industry due to many serious incidents every year. Thermal hazard...