Simultaneous quantification of five major constituents in stems of Dracaena plants and related medicinal preparations from China and Vietnam by HPLC–DAD

A high‐performance liquid chromatographic (HPLC) method was developed for the simultaneous quantification of five major bioactive constituents in the stems of resiniferous Dracaena plants from China and Vietnam, as well as those in the related traditional Chinese medicinal preparations. A diode array detector with the wavelength of 330 nm was used to monitor resveratrol, 7,4′‐dihydroxyflavone and pterostilbene, while loureirin A and loureirin B were monitored at 280 nm. The five constituents were separated on an Agela SB C₁₈ column by gradient elution using 0.008% (v/v) formic acid solution (A) and acetonitrile (B) as the mobile phase. The validation of the method included recovery, linearity, accuracy and precision (intra‐ and inter‐day variation). The range of recoveries of this method was 98.1–104.9%, with all the constituents showing good linearity (r² > 0.9999). The accuracy and precision were satisfactory, with the overall intra‐ and inter‐day variation being less than 4%. The present method has been successfully applied for the determination of all five constituents in 21 related herbal samples including 10 D. cochinchinensis stem samples, seven D. cambodiana stem samples and four purchased medicinal preparations. The contents of these constituents were analyzed using principal component analysis, which can efficiently identify raw herb of Dracaena from different sources. The study may be considered helpful to the quality control of Dracena plants and its medicinal preparations. Copyright © 2009 John Wiley & Sons, Ltd.     

A new hydroxybenzoic acid glycosides from the plant of Trifolium lupinaster

<正>A new 5-O-(β-D-glucopyranosyl)-6'-O-benzoyl-2,5-dihydroxybenzoic acid was isolated from the ethyl acetate extract from the whole plants of Trifolium lupinaster L.Its structure was determined and deduced on the basis of their spectral data.     

以PBL法进行药学实验基本技能教学的探索与实践*

根据西部少数民族地区院校的客观条件和教学特点,提出用以问题为导向的教学法(PBL)进行药学基本技能实验教学。实践证明,实验组(PBL法)的实践基本技能操作水平和发现、分析并解决问题的能力均显著高于对照组(传统教学法)。该法对提高西部少数民族地区药学本科生的创新能力具有较大意义,对其他地区药学本科生创新能力的培养也有一定的借鉴作用。     

有限气相反应速率条件下MFF模型应用方法的研究

本文使用"CO相对燃烧速率"的概念和通用的"有效影响参数转化方程",将带有气相反应速率无穷快假设的移动火焰锋面(MFF)模型成功地扩展应用到有限气相反应速率条件的计算中。对于多组不同有限气相反应速率、以及不同粒径的碳粒燃烧计算,MFF模型扩展应用的预报结果都与严格连续膜模型符合较好,碳粒着火温度的预报也更为准确。     

Cosolvent Effect on the Tautomerism of Ethyl Acetoacetate in Supercritical CO_2

There are some unique advantages for chemical reactions in SCFs. For example, reaction rates, yields, and selectivity can be tuned by pressure or small amount of cosolvent. SCFs can be used to replace environmentally undesirable solvents. It is not surprised that in recent years the use of SCFs as solvents for chemical reaction media has received much attention. However, mechanism for the effect of pressure and cosolvents on chemical reactions is not very clear. Tautomeric reactions are id…     

槲皮素化学修饰碳糊电极吸附溶出伏安法测定痕量铅

建立了用槲皮素修饰碳糊电极测定痕量铅的新方法 ,在 0 .1 0mol L甲酸盐缓冲液 (pH 4.3 )中 ,于 -0 .1 0V(vs.SCE)搅拌富集 ,再在 -0 .70V静止还原 40s后 ,阳极化扫描 ,于 -0 .42V左右获得一灵敏的铅阳极溶出峰。在最佳条件下 ,富集不同时间 ,其二次导数峰电流与Pb2 + 在 1 .0× 1 0 - 8～ 8.0× 1 0 - 7mol L和 2 .0× 1 0 - 9～ 6.0× 1 0 - 8mol L两个范围内呈线性关系 ,检出限为 8.0× 1 0 - 1 0 mol L(S N =3 )。同时初步探讨了电极反应机理。     

硝基吖啶酮差示脉冲伏安法测定核酸的研究

采用循环伏安法对合成的硝基吖啶酮(NACR)的电化学行为进行研究,建立硝基吖啶酮差示脉冲伏安法测定核酸的新方法。在pH 4.8的PBS缓冲液中,硝基吖啶酮与ctDNA能够相互作用形成超分子复合物,使硝基吖啶酮在0.043 V处的氧化峰电流下降,峰电流的下降值同ctDNA的浓度在5.0×10-5mg/L~6.5×10-6mg/L范围内呈良好的线性关系,检出限为2.0×10-7mg/L,相关系数为0.9974,已用于实际样品DNA的测定,故硝基吖啶酮有望成为一种新型的生物小分子电化学探针。     

Simultaneous determination of dopamine and serotonin using a carbon nanotubes-ionic liquid gel modified glassy carbon electrode

An electrochemical sensor based on carbon nanotubes (CNTs)-ionic liquid (IL) composite has been developed for the simultaneous determination of serotonin (5-HT) and dopamine (DA). The CNTs-IL composite modified electrode presents excellent selectivity and sensitivity towards 5-HT and DA and eliminates the interference of ascorbic acid. The parameters which influence the determination of 5-HT and DA have been investigated. Under optimized conditions, linear calibration graphs were obtained in the range from 20 nM to 7 µM, with a detection of limit of 8 nM, for 5-HT, and in the range from 0.1 to 12 µM, with a detection of limit of 60 nM, for DA. The electrode has been applied to the assay of 5-HT and DA in human blood serum with good results.