析相微萃取-石墨炉原子吸收法测定地质样品中痕量金

以MIBK为络合剂和提取剂,乙醇为助溶剂,建立了析相微萃取-石墨炉原子吸收法测定地质样品中痕量金的分析方法。详细探讨了金的不同析相微萃取体系的特性及析相规律,优化了金-MIBK体系的最佳析相微萃取条件及石墨炉升温程序。所建立的方法线性范围为0.006~1.0μg/L,检出限为0.0013μg/L,相对标准偏差为1.5%(n=11),用于国家地质标准参考物质(GBW07289)的测定,分析结果与推荐值吻合。     

Host properties of cucurbit [7] uril: fluorescence enhancement of acridine orange

The inclusion behavior of cucurbit [7] uril with acridine orange was investigated by fluorescence spectrometry in acetate buffer solution. It was found that the fluorescence intensity of acridine orange regularly increased upon the addition of cucurbit [7] uril accompanying with blue-shift of the position of the emission maximum. The results indicate the formation of the complex at a 1:1 complex stoichiometry and the association constant was calculated by applying a deduced equation. From the temperature dependence of the equilibrium constants, ΔH and ΔS values were obtained, indicating an enthalpic driving force for complexation. Meanwhile, the possible interaction mechanism was also discussed.     

Terpenoids from Two Dicranopteris Species

Two new compounds, (6S,13S)‐6‐{[β‐D ‐glucopyranosyl‐(1→4)‐α‐L ‐rhamnopyranosyl]oxy}cleroda‐3,14‐dien‐13‐ol ( 1 ) and kadsuric acid 3‐methyl ester ( 2 ), together with nine known compounds, (6S,13E)‐6‐{[β‐D ‐glucopyranosyl‐(1→4)‐α‐L ‐rhamnopyranosyl]oxy}cleroda‐3,13‐dien‐15‐ol ( 3 ), (6S,13S)‐6‐[6‐O‐acetyl‐β‐D ‐glucopyranosyl‐(1→4)‐α‐L ‐rhamnopyranosyl]oxy}‐13‐{[α‐L ‐rhamnopyranosyl‐(1→4)‐β‐D ‐fucopyranosyl]oxy}cleroda‐3,14‐diene ( 4 ), (6S,13S)‐6‐{[6‐O‐β‐D ‐glucopyranosyl‐(1→4)‐α‐L ‐rhamnopyranosyl]oxy}‐13‐{[α‐L ‐rhamnopyranosyl‐(1→4)‐β‐D ‐fucopyranosyl]oxy}cleroda‐3,14‐diene ( 5 ), 15‐hydroxydehydroabietic acid ( 6 ), 15‐hydroxylabd‐8(17)‐en‐19‐oic acid ( 7 ), junicedric acid ( 8 ), (4β)‐kaur‐16‐en‐18‐oic acid ( 9 ), (4β)‐16‐hydroxykauran‐18‐oic acid ( 10 ), and (4β,16β)‐16‐hydroxykauran‐18‐oic acid ( 11 ) were isolated from the fronds of Dicranopteris linearis or D. ampla. Their structures were established by extensive 1D‐ and 2D‐NMR spectroscopy. Compounds 1 and 3 – 8 showed no anti‐HIV activities.     

A new triterpene from the leaves of Craibiodendron yunnanense

A new triterpene, taraxast-20(30)-en-3β,12β-diol (1), and eight known compounds were isolated from the leaves of Craibiodendron yunnanense. Their structures were established on the basis of spectral evidence. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 35–37, January–February, 2008.     

A Method for Quantifying Azoxystrobin Residues in Grapes and Soil Using GC with Electron Capture Detection

A relatively simple method for the determination of azoxystrobin residues in grapes and soil using gas chromatography equipped with electron capture detector (GC-ECD) is described. Samples were extracted with acetone, and further partitioned with dichloromethane and petroleum ether. The extracts were then cleaned up in a glass clean-up column filled with active charcoal and silica gel, and eluted with dichloromethane/ethyl acetate (70:30, v/v). The eluate was collected and concentrated for GC-ECD analysis. The results showed good linearity (r ² = 0.9998) over the concentration range of 6.25–400 ng mL^?1. The limits of detection (LOD) and quantification (LOQ) of azoxystrobin were 3 and 10 ng mL^?1. Recovery from soil and grape samples was in the range of 83.52–107.36 and 82.21–107.31%, with corresponding relative standard deviations (RSD) of 5.21–9.11 and 4.53–5.90% for the three fortified levels. Inter- and intra-day RSDs were in the range of 0.87–6.76 and 2.01–5.46%. The accuracy and sensitivity of the GC-ECD method was independently confirmed by LC and GC-MS. It was demonstrated that the proposed method was simple and efficient, and particularly suitable for detecting azoxystrobin residues in grapes and soil.     

One-pot synthesis of diaryl ketones from aldehydes via palladium-catalyzed reaction with aryl boronic acids

A Pd-catalyzed coupling-type reaction of aldehydes and organoboronic acids was achieved in the presence of P(1-nap)₃, using Cs₂CO₃ in toluene, providing diaryl ketones with yields ranged from moderate to excellent. The efficiency of this reaction was demonstrated by the compatibility with nitro, cyano, trifluoromethyl, fluoro and chloro groups. Moreover, the rigorous exclusion of air/moisture is not required in these transformations.     

中空石墨碳材料作为电催化剂载体在直接乙醇燃料电池中的应用

以间苯二酚、苯酚与甲醛为前体,合成了一种中空石墨碳材料(hollow graphitic carbon,HGC).透射电镜(TEM)、N2吸附-脱附和Raman光谱测试结果表明,所制备的HGC为中孔结构,平均孔径为36nm.与商品Vulcan XC-72R相比,HGC中孔结构丰富,石墨化程度高.分别以HGC和XC-72R为载体制备了总金属载量为45%的PtSn/C电催化剂,X射线衍射和TEM结果表明这两个样品的平均粒径和晶格常数相近.单池性能测试表明,以45%PtSn/HGC为阳极催化剂的直接乙醇燃料电池的最大功率密度达到了62mW/cm2,与PtSn/XC-72R的54mW/cm2相比提高了近15%.     

焙烧温度对乙苯脱氢催化剂Fe2O3-K2O性能的影响

用混合法制备了Fe2O3-K2O乙苯脱氢催化剂,并用压汞法、X射线衍射、穆斯堡尔谱、程序升温还原和热重-差热分析等表征手段,考察了焙烧温度对催化剂的催化活性、比表面积、体相结构和还原性能的影响.结果表明,随着焙烧温度的升高,催化剂的比表面积逐渐减小,平均孔径逐渐增大;尖晶石K2Fe22O34中正四面体Fe3 的含量逐渐减少,正八面体Fe3 的含量逐渐增多,催化剂逐渐变得容易被还原;催化剂的催化活性差别不大,但达到平稳时所需的诱导期逐渐缩短.过高的焙烧温度不利于催化剂的稳定性.     

柱切换高效液相色谱法测定人血浆中布洛芬对映体浓度

建立了柱切换高效液相色谱法测定人血浆中布洛芬对映体浓度的方法。以对溴苯甲酸为内标,样品经醋酸钠缓冲液酸化后,用V(正己烷)∶V(异丙醇)=95∶5萃取。以Chiralcel OJ-H柱(Daicel Chemicals,250mm×4.6mm,5μm)为分析柱,UltimateTM SiO柱(50mm×4.6mm,5μm)为预处理柱;流动相为V(正己烷)∶V(异丙醇)∶V(三氟醋酸)=96.5∶3.5∶0.1,流速为0.5mL/min;预处理流动相为V(正己烷)∶V(异丙醇)=99.5∶1,流速为1mL/min;柱切换时间为1.70~4.09min;紫外检测波长为230nm。布洛芬消旋体和S-( )-布洛芬标准曲线线性范围分别为0.21~20mg/L和0.10~10mg/L;日内RSD小于6.5%,日间RSD小于6.1%;方法回收率为93.3%~107.1%,萃取回收率为80.0%~86.6%。本法简便、准确,重现性好,可用于布洛芬对映体人体药代动力学研究。     

Uracil Grafted Carbon Electrode:Electrocatalytic Behavior of Tryptophan,Tyrosine, Catecholamine and Related Compounds

基于尿嘧啶作为一种碱基,具备一定的分子识别能力,制备了一种新颖的尿嘧啶共价修饰电极,用X射线光电子能谱和电化学方法进行了表征,并研究了酪氨酸、色氨酸、儿茶酚胺（如多巴胺,肾上腺素,去甲肾上腺素）及相关的化合物尿酸、抗坏血酸在该电极上的电化学行为,获得相应的氧化电位、电流灵敏度、线性范围和检测限等信息。其中,色氨酸检测线性范围：1.8 - 120 mM,检测限（s/n=3）：0.8 mM;酪氨酸检测线性范围：1.8 - 89mM,检测限（s/n=3）：0.8 mM。实验表明,尿嘧啶修饰电极能催化氧化上述电活性物质,但催化能力不同,据此,我们讨论了尿嘧啶与上述物质的相互作用,详细探讨了催化机理,扩展了对基于分子识别的传感器的研究。