共查询到19条相似文献,搜索用时 125 毫秒
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穿心莲内酯的电化学研究 总被引:6,自引:0,他引:6
用单扫描示波极谱法在0.05mol/LNH4CL+0.25mol/LNH3.H2O中,穿心链内酯有一灵敏的还原峰,25℃时,峰电位为-1.60V(vs.SCE),峰电流与浓度在0.01~1.2mg/L和1.4~26mg/L范围内有良好的线性关系,检测限为6ng/mL。用本法测定天然中药穿心链中总内酯的含量,其结果令人满意。实验证明穿心链内酯的电极过程为可逆的逐级电子过程,H2O2可催化该还原峰,另 相似文献
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光泽精与在肾上腺素自氧化体系中(pH=10.20)产生的超氧阴离子自由基反应,其氧化产物在 -1.16 V(vs.SEC)和-1.60V(vs. SEC)处有两个还原峰,其中-1.16 V处的还原峰是光泽精被氧化的中 间产物的双电子还原峰,-1.60V处的还原峰是最终产物 N-甲基吖啶酮(NMA)的双电子还原峰。形成 反应中间体和 NMA的反应是一级反应,其反应速度常数分别为 2.07× 10-4s-1和 2.23 × 10-5s-1。 相似文献
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用甘草次酸(A)和甘草次酸甲酯(B)还原制得11-脱氧甘草次酸(1)和11-脱氧甘草次酸甲酯(2)。以此为原料进行酰化,合成了十种3-位酯化衍生物,再与碱金属氧化物反应合成了7种盐类衍生物。用IR,HNMR,MS和元素分析确证了它们的结构。 相似文献
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甘草次酸衍生物的合成 总被引:7,自引:0,他引:7
豆科植物甘草中含有大量甘草次酸(Glycyrrhetinic Acid)。近代药理实验表明,甘草的抗炎症、抗溃疡以及抗变态反应等功效,主要归因于甘草中所含的甘草甜素,甘草次酸及其衍生物。多年来,国内外学者对甘草次酸 相似文献
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甘草酸的电化学行为研究 总被引:3,自引:0,他引:3
用循环伏安法、单扫描示波极谱法研究了甘草酸(glycyrrhizic,GA)在汞电极上的电化学行为及反应机理.证明甘草酸在pH=4~12的缓冲溶液(H3BO3+H3PO4+乙酸+NaOH)中有吸附峰,且示波极谱导数峰值与甘草酸浓度在8.3×10-5~1.2×10-6mol/L范围内成正比,使用悬汞电极(HMDE)线性扫描伏安法可使检测下限达2.4×10-6mol/L.根据实验结果首次提出了甘草酸在汞电极上的反应机理.该机理同时被紫外光谱证明,得到合理解释 相似文献
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采用循环伏安法研究了大黄素在滴汞电极上的电化学行为,应用线性扫描法提出了药用植物大黄中大黄素不需分离的直接测定方法。大黄素在pH 5.72 B-R缓冲溶液中,在-0.434 V(vs.Ag/AgCl)处产生一灵敏的极谱峰,峰电流与大黄素浓度在1×10-6~1.5×10-5mol.L-1范围内呈线性关系。试验结果表明:该体系属具有吸附性的准可逆过程体系。 相似文献
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《Electroanalysis》2003,15(3):208-218
The electrochemical oxidation and electrochemiluminescent behavior of homogentisic acid (HGA) has been studied in aqueous solutions over a wide pH range by linear sweep voltammetry, cyclic voltammetry, chronocoulometry at a glassy carbon electrode, by controlled potential electrolysis at a large area spectroscopic graphite electrode, and by spectroelectrochemistry at an optically transparent drilled holes graphite (DHG) electrode in a thin‐layer cell. The studies reveal that the electrochemical oxidation of HGA at carbon electrodes is a reversible process involving two‐electron, two‐proton transfer. In addition to the electrochemical oxidation, the chemical oxidation of HGA by dissolved oxygen was investigated by spectroscopic method combined with voltammetry. It was revealed that HGA is fairly stable in strongly acidic media but readily oxidized by dissolved oxygen in alkaline media giving rise to 1,4‐benzoquinone‐2‐acetic acid, the same product as that of electrooxidation of HGA. This oxidation product is stable in acidic, neutral and weakly alkaline media, but can further degrade in strongly alkaline media yielding oxalate as the final product. The electrochemiluminescent mechanism of HGA in the presence of Ru(bpy)32+ at a glassy carbon electrode was also investigated in detail, based on which a sensitive ECL method for determination of HGA was developed, and the detection limit was 3.0×10?8 mol L?1. 相似文献
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《Electroanalysis》2006,18(23):2385-2388
Electrochemical reduction of Deoxycholic acid (DCA), as important biological molecule has been studied in 0.05 M KH2PO4 aqueous methanol solution (1 : 1, v/v) at a multiwalled carbon nanotubes modified electrode. Based on cyclic voltammetry, Tafel plot, the possible mechanism of the electrochemical reduction of DCA was investigated, as well as DCA mechanical calculations. The transfer coefficient, α, the exchange current density, i0, the diffusion coefficient, D0 at the MWCNT modified GCE were determined as 0.505, 5.655×10?7 A/cm2 and 1.579×10?5 cm2/s, respectively. The results of chronoamperometric suggested that the reductive product of DCA was the corresponding hydroxymethyl compound in an over‐all four‐electron process. 相似文献
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茜素红S与壳聚糖相互作用的电化学行为研究 总被引:3,自引:0,他引:3
在pH5.0NaAc—HAc缓冲溶液中,茜素红S能与壳聚糖生成一种紫红色的复合物。复合物使茜素红S在-0.408 V处的还原峰峰电流降低。在选定的最佳条件下,用循环伏安法和线性扫描极谱法测定其峰电流的降低值与壳聚糖的浓度在0.5~7.5mg/L的范围内呈线性关系,线性回归方程为△ip^#=30.92 108.4CCTS(mg/L),相关系数0.9990;检出限0.4mg/L。据此建立一种快速、简便测定壳聚糖的方法。该方法可应用于实际样品的测定。 相似文献