On-line determination of organophosphorus pesticides in water by solid-phase microextraction and gas chromatography with thermionic-selective detection

This paper describes the extraction of 49 organophosphorus pesti-cides (OPPs) from water samples using solid-phase microextraction (SPME). Three fibers, including a 15-μm XAD-coated fiber, a 85-μm polyacrylate-coated fiber, and a 30-μm polydimethylsilox-ane-coated fiber (PDMS), were evaluated here. The effects of stirring and the addition of NaCl to the sample were examined for the polyacrylate-coated fiber. The precision of the technique was examined for all three fibers and the extraction kinetics were investigated using the XAD- and polyacrylate-coated fibers. With some exceptions, the XAD- and polyacrylate-coated fibers performed better than the PDMS-coated fiber. The superiority of the XAD-nd polyacrylate-coated fiber. The superiority of the XAD- and polyacrylate-coated fibers over the PDMS-coated fibers can be attribuibuted to the aromatic functionalities of the XAD and the polar functionalities in the polyacrylate. The relatively high percent RSDs indicate that the SPME technique needs to be further refined before it can be used for anything other than screening. A more effective form of agitation than mechanical stirring may be neccessary to reduce variability and achieve a faster equilibrium between the sample and the SPME fiber.     

Determination of Gossypol in Trace Level by Flow Injection Analysis with Chemiluminescence Detection

Gossypol, [1, 1′, 6, 6′, 7,7′-hexahydroxyl-5,5′-diisopropyl-3,3′-dimethyl-(2,2′-binaphtha- lene)-8,8′-dicarboxaldehyde] is a polyphenolic yellow compound naturally occurring in various parts of cotton plants1. The compound has been associated with     

铽(Ⅲ)-1,4-双(1′-苯基-3′-甲基-5′-氧代吡唑-4′-基)丁二酮-[1,4]体系荧光性质的研究及应用

本文研究了Tb(Ⅲ)-1,4-双(′-苯基-3′-甲基-5′-氧代吡唑-4′-基)丁二酮-[1,4](BPMPBD)-溴化十六烷基三甲胺(CTMAB)体系的荧光性质,探讨了响影体系荧光性质的诸因素,确定了最佳实验条件。该体系中Tb(Ⅲ)浓度以2.0×10~(-5)～1.0×10~(-10)mol/L范围内与其荧光强度呈线性关系,检测限可达到5.0×10~(-11)mol/L。应用于合成样品中微量Tb(Ⅲ)的分析,结果令人满意。     

非水介质毛细管电泳电导检测舒血宁片中槲皮素含量

以甲醇：水＝70：30的体系为分离介质，柠檬酸－三（羟甲基）氨基甲烷（Citric acid-Tris)为支持电解质，使用电导检测，对槲皮素及其制剂舒血宁片进行了毛细管电泳分离检测，对电泳介质的种类、浓度、表观pH值以及操作电压和进样时间对分离的影响进行了研讨，并对分离检测机理进行了探讨。建立的测定槲皮素的方法的线性范围为：8．0－160．0mg/L；峰面积的RSD（n=6)为1．7％，检出限为1．0mg/L；样品加标回收率为92．8％－98．2％。     

In-channel indirect amperometric detection of nonelectroactive anions for electrophoresis on a poly(dimethylsiloxane) microchip

In the present paper, we describe a microfluidics-based sensing system for nonelectroactive anions under negative separation electric field by mounting a single carbon fiber disk working electrode (WE) in the end part of a poly(dimethylsiloxane) microchannel. In contrast to work in a positive separation electric field described in our previous paper (Anal. Chem. 2004, 76, 6902-6907), here the electrochemical reduction reaction at the WE is not coupled with the separation high-voltage (HV) system, whereas the electrochemical oxidation reaction at the WE is coupled with the separation HV system. The electroactive indicator is the carbon fiber WE itself but not dissolved oxygen. This provides a convenient and sensitive means for the determination of nonelectroactive anions by amperometry. The influences of separation voltage, detection potential, and the distance between the WE and the separation channel outlet on the response of the detector have been investigated. The present detection mode is successfully used to electrochemically detect F-, Cl-, SO4(2-), CH3COO-, H2PO4-. Based on the preliminary results, a detection limit of 2 microM and a dynamic range up to three orders of magnitude for Cl- could be achieved.     

2，4，6－三苯基氧鎓盐分子内旋转受阻对其发光行为的影响

研究了４－位苯基取代基旋转受阻和旋转自由的２，４，６－三苯基氧盐的光物理性质。实验结果表明，当４－位苯基取代基旋转受阻时，氧盐化合物在激发态时引起的分子内极化程度比４－位取代基旋转自由的氧盐化合物大，即在激发态时旋转受阻氧盐化合物发生的分子内电荷转移能力较强；４－位取代基旋转自由的化合物的荧光量子产率随溶剂粘度的增大而有所增大，但旋转受阻化合物在相同的条件下则出现相反的结果。实验结果还表明，４－位取代苯基旋转受阻对化合物的荧光发射不利。     

Synthesis of novel copoly(styrene-maleic anhydride) materials and their luminescent properties

Two series of new high fluorescent polymeric materials based on copoly(styrene-maleic anhydride) (SMA) were prepared by the condensation of SMA with fluorescent groups. One series consists of 1,8-naphthalimides derivatives that are linked with SMA. The other series were prepared by the condensation of SMA with 3,4,9,10-perylene tetracarboxylic mono-anhydride mono-imide. These simple routes to copolymer of styrene and maleic anhydride containing pendent luminescent moiety are promising in increasing fluorescent quantum yield in solid state and processing, in which styrene is employed as “diluents”. The luminescent and the preliminary photovoltaic properties of these copolymers have been investigated.     

Size of Micelles Determined by Static Fluorescence Quenching

We developed a new method to measure the average aggregation number of large rod-like micelles using static fluorescence self-quenching of a solubilized fluorophore. The method is based on the increase of self-quenching of micelle-solubilized pyrene through excimer formation. We consider the effect of random distribution of pyrene in micelles and the micellar size distribution. The measured average aggregation <n> _M is based on a new M-weighted raging similar to our exponential-weighted averaging in the transient decay method. We apply this method to study the effect of a large concentration of salt on the average aggregation behavior of sodium dodecyl sulfate (SDS) and cetyle tetraammonium bromide (CTAB). The sizes increase with increasing ionic concentrations. For SDS, we used the thermodynamic model developed by Missel et al. to calculate < n > _M which we compare with experimental results.     

荧光法研究Ge-132对牛血清白蛋白Maillard反应的抑制作用

人体内氨基酸及蛋白质的非酶糖化反应(Maillard反应)与糖尿病及其并发症的关系已经引起广泛注意[1].有机锗化合物β-羧乙基锗倍半氧化物(Ge-132)具有预防糖尿病及调节糖代谢的作用[2].