银胶中苯甲酸表面增强拉曼峰强的温度效应

本文测定了银胶中对应于苯甲酸分子不同部分振动模的表面增强拉曼峰强度随温度变化的情形。当温度上升时,表面增强拉曼峰强一般随之降低,但对不同之振动模有着不同的速率。此结果以这样的图象来解释:表面增强拉曼效应是距离(指与银胶颗粒之表面距离)的函数,并且化学与物理机制均起作用,前者为近距离效应而后者为长距离效应。文中半定量地讨论了此二机制对苯甲酸分子不同部分的增强效应的影响。     

Synthesis,spectroscopic characterization and in vitro antitumour activity of di-n-butyltin and diethyltin trimethoxybenzoates: X-ray structure analysis of bis[di-n-butyl(3,4,5-trimethoxybenzoato)tin] oxide

Di-n-butyltin(IV) and diethyltin(IV) 2,3,4-, 2,4,5- and 3,4,5-trimethoxybenzoates [(CH₃O)₃C₆H₂COO]₂SnR [Type a] and {[(CH₃O)₃C₆H₂COO]R₂Sn}₂O [Type b] have been synthesized and characterized spectroscopically. The crystal structure of bis[di-n-butyl(3,4,5- trimethoxybenzoato)tin] oxide has been determined. The triclinic unit cell contains one centrosymmetric dimer; a = 15.919(2) Å, b = 11.711(3) Å, c = 13.475(1) Å, and α = 63.63(2)°, β = 67.49(1)°, γ = 76.61(2)°. The geometry of the dimer is very similar to that of bis[di-n-butyl(5-methoxysalicylatotin] oxide), with two different types of five-coordinate tin atoms and one central planar Sn₂O₂ ring.     

Separation of nebramycin components by ion-exchange thin-layer chromatography

A thin-layer chromatographic method on chromatoplates coated with Dowex 50 × 8 ion-exchange resin, suitable for the separation of 5 nebramycin components, was developed.     

Gas chromatographic analysis of C1–C20 carboxylic acids esterified in aqueous solutions as isobutyl esters

Summary C₁–C₂₀ carboxylic acids have been esterified in aqueous solutions with i-butanol. Gas chromatographic analyses have been performed from a single chromatogram. It has been established that esterification in the concentration range of [H₂O]/[i-BuOH]=0.01–10.3 can be utilized for the quantitative determination of these carboxylic acids.The presence of water does not interfere in the range of [H₂O]/[i-BuOH]=0.01–1.03.In the cases of [H₂O]/[i-BuOH]>1.03, anhydrous sodium sulfate has been used for binding the water, in an amount of [Na₂SO₄]_anh./[H₂O]0.2.     

胶束电动色谱法测定五维他口服溶液中维生素B_1、B_2、B_6、烟酰胺、泛酸钙与苯甲酸钠

建立了胶束电动色谱(MEKC)法通过波长切换同时测定五维他口服溶液中的维生素B_1、B_2、B_6、烟酰胺、泛酸钙及苯甲酸钠含量的方法,并优化了检测波长、十二烷基硫酸钠(SDS)的浓度、分离电压、缓冲液浓度及pH值等实验条件。最佳分离条件为以未涂渍的标准熔融石英毛细管柱(75μm×50 cm,有效长度42 cm)为分离通道;40 mmol/L硼酸+40 mmol/L硼砂+20 mmol/L SDS(pH 9.0)为运行缓冲液,分离电压20 kV,柱温25℃,检测波长为270 nm(维生素B_1、B_2、B_6、烟酰胺及苯甲酸钠)和200 nm(泛酸钙),电动进样10 kV、进样时间10 s。结果显示,6种化合物可在13 min内实现基线分离,且在一定质量浓度范围内线性良好,相关系数(r)不小于0.998 9;3个加标水平下的平均回收率为97.0%～103%,RSD为0.60%～1.8%。该方法快速、准确,可用于五维他口服溶液中维生素B_1、B_2、B_6、烟酰胺、泛酸钙及苯甲酸钠的含量测定。     

Chemical modification of polymeric microchip devices

Analytical polymeric microchips in both fluidic and array formats offer short analysis times, coupling of many sample processing and chemical reaction steps on one platform with minimal sample and reagent consumption, as well as low cost, minimal fabrication times and disposability. However, the invariable bulk properties of most commercial polymers have driven researchers to develop new modification strategies. This article critically reviews the scope and development of chemical modifications of such polymeric chips since 2003. Surface modifications were based on chemical derivatization or activation of surface layers with reagent solutions, reactive gases and irradiation. Bulk modification of polymer chips used newly incorporation of monomers with selective chemical functionalities throughout the bulk polymer material and integrated the chip modification and fabrication into a single step. Such modifications hold a great promise for establishing a true ‘lab-on-chip’ as can be seen from many novel applications for modulating electroosmosis, suppressing protein adsorption in microchip capillary electrophoretic separations, extraction of analytes and for zone-specific binding of enzymes and other biomolecules.     

Syntheses,Crystal Structures,and Magnetic Properties of Three Metal‐Nitroxide Complexes with the V‐shaped 4, 4′‐Oxybis(benzoate)

Three new metal–nitroxide complexes {[Ni(NIT4Py)₂(obb)(H₂O)₂] · 1.5H₂O}_n ( 1 ), {[Co(NIT4Py)₂(obb)(H₂O)₂] · 2H₂O}_n ( 2 ), and [Co(IM4Py)₂(obb)₂(H₂O)₂][Co(IM4Py)₂(H₂O)₄] · 10H₂O ( 3 ) with the V‐shaped 4,4′‐oxybis(benzoate) [NIT4Py = 2‐(4′‐pyridyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide, IM4Py = 2‐(4′‐pyridyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxide, and obb = 4, 4′‐oxybis(benzoate) anion] were synthesized and structurally characterized. Single‐crystal X‐ray analyses indicate that complexes 1 and 2 crystallize in neutral one‐dimensional (1D) zigzag chains, in which the nitroxide–metal–nitroxide units are linked by the V‐shaped 4,4′‐oxybis(benzoate) anions, whereas complex 3 consists of isolated mononuclear [Co(IM4Py)₂(obb)₂(H₂O)₂]^2– anions and [Co(IM4Py)₂(H₂O)₄]²⁺ ions. Magnetic measurements show that complexes 1 and 2 both exhibit weak antiferromagnetic interactions between the metal ions and the nitroxides.