Determination of 12 additives in beverages by evaporation-assisted dispersive liquid-liquid microextraction based on the solidification of floating organic droplets combined with liquid chromatographyEI北大核心CSCD

An analytical method for the simultaneous determination of 12 additives in beverages was developed using evaporation-assisted dispersive liquid-liquid microextraction based on the solidification of floating organic droplets EVA-DLLME-SFOcombined with high performance liquid chromatography HPLC. The samples were extracted twice with 70%V/Vmethanol aqueous solution and extracted by EVA-DLLME-SFO method after the combination of the extractsand finally determined by HPLC. Extraction parameterssuch as types and amounts of extractantevaporant and heating agentthe concentration of saltand the extraction time were optimized. Under the optimized conditionsthere were good relationships in the ange of 0.25-50 μµg/mL with the limits of detection of 1.5 to 13.6 mg/kg and limits of quantification of 5.2 to 45.3 mg/kg. The recoveries at three spiked levels1025 and 50 mg/kgwere 76.8% to 101.2% with the relative standard deviations of 0.11% to 4.7%. The method can be used for rapid detection of 12 additives in beverages. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Pd nanoparticles on boron doped graphene catalyst for electrochemical detection of hydrogen peroxide prepared by electroless deposition methodEI北大核心CSCD

Taking advantage of large conjugated structure and reductivity of boron-doped graphenethe palladium nanoparticles/boron-doped graphene catalyst was prepared by electroless deposition method using boron-doped graphene as reductant and stabilizer. The average size of palladium nanoparticles highly dispersed on the surface of boron-doped graphene was about 6.5 nm. The electrochemical sensor was prepared by modifying the as-formed catalyst on the surface of glassy carbon electrode. The obtained electrochemical sensor exhibited an excellent electrochemical catalytic activity for H2 O2 . It exhibited high sensitivity with the detection limit as low as 830 nmol/L and good linearity in the range of 2.5-300 μµmol/L for detection of H2 O2 . It could be utilized for the determination of H2 O2 in milk samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

三维还原氧化石墨烯/β-环糊精复合物的合成及其电化学检测水中左氧氟沙星北大核心CSCD

成功构筑了β-环糊精修饰的三维还原氧化石墨烯复合材料(3D-rGO/β-CD),并对该复合材料进行扫描电子显微镜、傅里叶红外光谱、热重分析和拉曼光谱分析等一系列的表征,分析了其形貌和结构的特征。进一步将其修饰到玻碳电极(GCE)表面,构建了一种新型电化学传感器(3D-rGO/β-CD/GCE)。利用3D-rGO/β-CD/GCE电化学传感器,通过微分脉冲伏安法(DPV)对左氧氟沙星(LEV)进行了检测。其中,具有多孔结构的三维还原氧化石墨烯具有优异的导电性能、比表面积大、化学稳定性好等优良的性质,而修饰的β-环糊精能在其环形腔内与客体分子结合形成超分子包合物,进而可以对LEV进行有效识别。研究结果显示,在最优实验条件下,3D-rGO/β-CD/GCE对左氧氟沙星的检测具有较宽的线性范围(1~150μmol/L),且检测限可达0.33μmol/L,同时该修饰电极还表现出良好的选择性和稳定性。此外,成功将其应用于实际水样中LEV的检测,表明该传感器具有一定的应用潜力。     

冰冻人血清中尿酸标准物质复制的定值EI北大核心CSCD

为了满足该标准物质的需求,进行了第二次尿酸血清标准物质的复制。针对复制的尿酸血清标准物质,基于单四极杆质谱的液相色谱-同位素稀释质谱法(LC-IDMS),用乙腈沉淀法去除蛋白质,BEH C18色谱柱和电喷雾离子源负离子模式(ESI^(-)),同位素稀释的单点校准法进行定值、均匀性检验、稳定性检验以及不确定度评定等研究。此定值方法经过CCQM-K109(血清中尿酸分析)国际关键比对进行验证。复制的2种不同浓度水平尿酸(肾病患者和正常人)血清标准物质的定值结果分别为(73.5±1.3)μg/g,(47.5±1.1)μg/g,其均匀性和稳定性评估结果良好。     

CoMn@NC催化5-羟甲基糠醛常压氧化为2, 5-呋喃二甲酸二甲酯

2, 5-呋喃二甲酸二甲酯(DMFDCA)这一生物质衍生的增值化学品是石油基聚合物单体对苯二甲酸(TPA)的理想替代品。本研究采用一步共热解法合成了两种廉价金属修饰的氮掺杂多孔碳催化剂CoMn@NC,并将其用于5-羟甲基糠醛(HMF)在温和条件下的需氧氧化。由Co₃Mn₂@NC-800催化HMF在50 ℃和常压氧气的条件下反应12 h后,得到产率为85%的DMFDCA。多孔催化剂的高比表面积提高了传质效率。Co纳米粒子(NPs)和呈原子级分散的Mn与掺杂在碳中的氮配位形成M―N_x。富含吡啶氮的碳基体中的缺电子金属位点有利于HMF和氧的活化。氧形成的超氧自由基阴离子的存在确保了半缩醛中间体和5-(羟基甲基)-2-糠酸甲酯(HMMF)的羟甲基的脱氢氧化,从而高选择性得到DMFDCA。该催化剂性能稳定,可适用于各种取代芳醇。该催化体系具有用于生产聚合物单体羧基酯的应用潜力。     

高效液相色谱-四极杆/静电场轨道阱高分辨质谱法快速分析三子散的入血成分及代谢产物

蒙药三子散由诃子、川楝子、栀子3味药材等比例组成,其临床用药主要采用口服给药方式,药物在体内的吸收、分布、代谢、排泄过程与药物发挥药理作用和疗效的产生密切相关,因此考察灌胃给药后的入血成分有助于阐明三子散的药效物质基础。研究采用血清药物化学研究思路,将Wistar大鼠分成空白组和给药组,给药组给予三子散水提物,腹主动脉取血,离心制备血清样品,采用高效液相色谱-四极杆/静电场轨道阱高分辨质谱(HPLC-Q/Orbitrap HRMS),在SHIMADZU GIST C₁₈色谱柱(150 mm×4.6 mm, 5 μm)上进行色谱分离;以甲醇和0.1%(v/v)甲酸水溶液为流动相进行梯度洗脱,柱温30 ℃,流速0.5 mL/min,进样量10 μL,采用加热电喷雾电离(HESI)源,正、负离子同时扫描。通过比对三子散含药血清和空白血清的图谱差异,查阅数据库、各类成分体内代谢途径、三子散成分的相关文献,采用Xcalibur 3.0软件进行峰提取、峰匹配等质谱数据处理,结合Compound Discover 3.0软件对化合物代谢途径的预测分析和裂解规律的推断,解析三子散水提液经大鼠灌胃后血清中的原型成分和代谢产物。结果表明,在给药大鼠血清样品中鉴定出55种入血成分,其中41种原型成分,14种代谢产物。入血的原型成分主要为鞣质类、环烯醚萜类和小分子酚酸类。该研究较为全面地阐释了三子散水提液在大鼠血中的移行成分,有助于揭示三子散的药效物质基础,为该药的临床应用提供参考。     

多相催化生物甘油选择性氧化制取1,3-二羟基丙酮的研究进展北大核心CSCD

1,3-二羟基丙酮(DHA)是一种重要的化工原料,广泛应用于医药、化妆品及食品等领域.通过催化选择性氧化甘油制备DHA是一条高效、经济的工艺路线,而催化剂的种类及反应方式被证明对DHA的产率有较大影响.因此,结合近些年来相关文献,系统阐述了热、光和电这3种催化反应方式在甘油氧化制取DHA上的研究进展,并重点介绍了热催化路径中所选用的催化剂、相关研究实例及反应机理.最后,对甘油制备DHA的多路径选择性氧化的研究前景进行了展望.     

国内外化学教师PCK评价量规的实证研究述评*

主要从化学教师PCK评价量规的建立方式、测查内容、特征属性,以及应用量规测查PCK水平实证研究的研究设计、研究目的等维度梳理了相关文献。综述表明:(1)国内外研究均较多基于已有成果建立量规,较少基于原始数据生成量规,对比国外,国内有关后者的研究更为稀缺;(2)国内外研究均较多测查KoC,KoL,KoS,而较少测查KoA,CTO以及整合水平;(3)国内外研究均较多应用化学学科专属型评价量规,少部分国内研究开发了化学主题专属型评价量规;(4)与国外相比,国内研究较少应用概念图法和定性定量混合型分析方法;(5)相对而言,国内研究更关注调查型研究,但较少探查PCK水平与其他变量的关系,较少关注干预型研究。文末据此对我国开发本土化的化学教师PCK评价量规用于实证研究与化学教师教育提出建议。     

“Ghost peaks” of olmesartan medoxomil: Two solution degradation products of olmesartan medoxomil via oxidation mediated by metal ions

Two unknown solution degradants were found during the dissolution testing in 0.1-M HCl for olmesartan medoxomil (OLM) tablets. The structure of the degradants was identified and characterized by liquid chromatography–ultraviolet (LC–UV), liquid chromatography with tandem mass spectrometry (LC–MS/MS), and nuclear magnetic resonance (NMR) and demonstrated to be cyclization of tetrazole and benzene in the olmesartan (OL) and OLM structures. A series of studies including stress studies, simulation studies, and mechanism-based studies were performed to reveal the potential mechanisms that lead to the formation of the unknown degradants. The study results demonstrated that the degradation was catalyzed with radicals that originated from the metal ions leached from the inner surface of high-performance liquid chromatography (HPLC) glass vials with dissolved oxygen under acidic condition. Prerinsing the glass vials with acidic solution dissolved with EDTA can effectively avoid the generation of such oxidative impurities. The present work provides new insights into the understanding of degradation pathways of OLM, which might support the development of OLM tablets.