Multifiber solid‐phase microextraction using different molecularly imprinted coatings for simultaneous selective extraction and sensitive determination of organophosphorus pesticides

Three types of molecularly imprinted solid‐phase microextraction fibers were fabricated through sol‐gel method using diazinon, parathion‐methyl, and isocarbophos as templates, respectively, and assembled together to construct a multifiber for analysis of organophosphorus pesticides in complex matrices. The multifiber provided large extraction capacity and high imprinting factor up to 3.89. In contrast, the imprinting factor of a single fiber was around 1.6, and the multi‐template imprinted coating showed no selectivity. The multifiber was applied to analyze pesticides in fruits and vegetables. The limits of detection, which ranged from 0.0052 to 0.23 µg/kg, were lower than those obtained by a single molecularly imprinted fiber, and much lower than those reported by other methods. The recoveries of five analytes in spiked apple, cucumber, Chinese cabbage, and cherry tomato samples were 75.1–123.2%. The study shows that the molecularly imprinted multifiber could achieve simultaneous selective extraction and sensitive determination of multiple targets in complex matrices for high‐throughput analysis.     

Open‐tubular capillary electrochromatographic application of a sol‐gel matrix with chilli peppers,garlic, or synthetic additives

This article describes a possible combination of two promising fields of analytical chemistry—the preparation of sol‐gel matrices with varying additives and their application in capillary electrochromatography. The inner surfaces of capillaries were coated with the sol‐gel solution containing either pure synthetic chemical additive—alliin or capsaicin—or an extract of their natural sources—garlic and chilli pepper, respectively. The modified capillaries were tested for interaction with two neurotransmitters, oligopeptides and nucleotides under conditions of open‐tubular capillary electrochromatography. Because both of the natural extracts also contain vitamin C and saccharose, the capillaries with sol‐gel modifiers containing each of these substances were also tested. The obtained results from the perspective of changes in the electrochromatograms and the effective mobilities of analytes are discussed with respect to mild conditions both in the preparation process of the sol‐gel matrix and during the separations.     

纳米Zn_(0.6)Co_xFe_(2.4-x)O_4晶粒的结构相变与磁性研究

采用溶胶 凝胶自燃烧法制备了纳米尺度的锌钴铁氧体Zn0 6 CoxFe2 4 -xO4 (x =0— 0 30 )粉体 ,分别在不同温度下进行了热处理 ,利用x射线衍射仪 (XRD)和振动样品磁强计 (VSM)对其物相结构和磁性进行了测量和分析 .实验结果表明 ,锌钴铁氧体Zn0 6 Co0 1 5Fe2 2 5O4 在 5 5 0— 80 0℃温度区间出现α Fe2 O3过渡相 ,在高于 80 0℃温度时生成单一尖晶石相锌钴铁氧体 ;随钴含量的增加 ,Zn0 6 CoxFe2 4 -xO4 的比饱和磁化强度先增后减 ,x =0 0 75— 0 1 5比饱和磁化强度较高 ;Zn0 6 CoxFe2 4 -xO4 在 1 30 0℃时x =0 0 75的矫顽力为 4 75 2 0A m ,x≥ 0 1 5时矫顽力在 1 2 0 0℃附近随温度缓慢上升 ,在 1 2 0 0— 1 30 0℃之间为平台状态 ,并且随钴含量的增加 ,矫顽力略有升高 .在x =0 1 0附近 ,可同时获得较高的比饱和磁化强度和较高的矫顽力     

Crystallization kinetics in ferroelectric thin films: Viability of atomic force microscopy

The pyrochlore to perovskite phase transformation was studied in lead zirconate titanate (PZT) thin films. The films were fabricated on platinum electrodes and annealed by rapid thermal processing (RTP). The phases which formed and their location in the film were analyzed using glancing angle XRD and depth profiling was demonstrated. Grain size and structure, nucleation sites and surface morphology were determined with transmission electron microscop (TEM) and atomic force microscopy (AFM). The role of AFM in this type of transformation study was assessed.

The PZT films crystallized with a (100) orientation which was preferentially nucleated at the platinum/film interface. RTP at 650°C for 15 s was sufficient to complete the transformation. However, columnar grain growth and improvements in the ferroelectric properties were obtained with increased RTP time. A PZT film with RTP at 650°C for 1 min possessed a remanent polarization of 25 μC/cm² and a dielectric constant of ε = 650.     

银颗粒表面尿嘧啶分子的SERS实验研究——KCl对尿嘧啶分子吸附状态的影响

利用表面增强喇曼散射(SERS)在灰银胶体系中研究了KCl对尿嘧啶分子吸附状态的影响,并将实验结果与Oh等人在黄银胶体系中的实验结果进行了详细比较.对这一实验现象进行了定性解释.     

Sol-Gel Derived Carbon Ceramic Electrode Bulk-Modified with Tris(1,10-phenanthroline-5,6-dione)iron(II) Hexafluorophos-phate and Its Use as an Amperometric Iodate Sensor

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｓｏｌ ｇｅｌｐｒｏｃｅｓｓｐｒｏｖｉｄｅｓａｖｅｒｓａｔｉｌｅｍｅｔｈｏｄｆｏｒｔｈｅｆａｂｒｉｃａｔｉｏｎｏｆｉｎｏｒｇａｎｉｃａｎｄｉｎｏｒｇａｎｉｃ ｏｒｇａｎｉｃｈｙｂｒｉｄｍａｔｅｒｉａｌｓｖｉａｔｈｅｈｙｄｒｏｌｙｓｉｓａｎｄｃｏｎｄｅｎｓａｔｉｏｎｏｆｓｕｉｔａｂｌｅｍｅｔａｌａｌｋｏｘｉｄｅｓ .1 3Ｔｈｅｓｅｍａｔｅｒｉａｌｓｐｏｓｓｅｓｓｎｏｔａｂｌｅａｄ ｖａｎｔａｇｅｓｏｖｅｒｏｔｈｅｒｉｎｏｒｇａｎｉｃ ｏｒｇａｎｉｃｍａｔｅｒｉａｌｓｆｏｒｔ…     

四氯化碳溶剂中溶胶法快速制备纳米TiO2光催化剂的结构表征

用钛酸四丁酯(Ti(OBu)4)在CCl4溶液中水解形成溶胶的方法，制备了纳米TiO2粉体。研究发现(Ti(OBu)4)水解脱醇时，醇不但在脱除过程中发生碳化，而且发生异构化；热处理时在711K后恒重，纳米TiO2粒子表面极易-OH化，表面-OH很难脱除。随着温度的升高，TiO2结构中的[TiO6]八面体的联接方式由角顶相连变为共棱相连，晶面间距越来越小，873K时与锐钛矿相的TiO2晶面间距与文献值相吻合，锐钛矿相TiO2结晶度最高。继续升温至873K时，发现TiO2锐钛矿相和金红石相共存。制备纳米TiO2的粒子晶粒度为8—14nm，基本不团聚，粒度均匀；而且在873—973K高温下焙烧没有明显的烧结长大，取得满意效果。     

辐照聚苯乙烯溶胶性质的SEC—LALLS法研究

聚苯乙烯是一种耐辐照的通用高分子材料。用其它方法来表征其微观反应参量,辐照剂量需要很大,周期长,而用SEC-LALLS法,则仅需凝胶点前知识,相应需要时间短,有关这方面的研究工作还未见文献详细报导。     

若丹明B掺杂的SiO2凝胶的荧光光谱研究

以正硅酸乙酯（TEOS）和有机染料若丹明B（Rhodamine B)为原料，彩溶胶－凝胶方法（the sol-gel method)制备了若丹明B掺杂的SiO2凝胶，研究了SiO2凝胶的荧光光谱。报道了若丹明B在SiO2凝胶中的荧光光谱比在水中的荧光光谱发生红移，尤其在制备过程中的不同阶段，若丹明B掺杂SiO2凝胶的荧光光谱的峰位发生的一系列变化，从而得到了若丹明B在水中及若丹明B在SiO2凝胶制备过程之中，直至SiO2凝胶制备完毕的荧光光谱发生变化的全过程。还报道了在反应中的磁力搅抖阶段，采用回流过程和不采用回流过程两种方法时，对所得若丹明B掺杂SiO2凝胶的荧光光谱的影响。