离子交换-原子捕集-火焰原子吸收光谱法测定水中的超痕量镍

在文中所述条件下,镍的原子捕集灵敏度较常规法高320倍,即在离子交换法浓缩仅40倍的情况下,可使镍的测定灵敏度提高12800倍,从而成功实现了ppt级超痕量镍的测定。     

Facile synthesis of ultra-long Cu microdendrites for the electrochemical detection of glucose

Ultra-long Cu microdendrites (MDs) were prepared by one-step electrodeposition on a glassy carbon electrode. The results demonstrated that the reduction potential, pH, and temperature of the electrolysis solution, as well as the amount of Cu²⁺ and citrate ions, play important roles in the formation of the Cu MDs. Notably, the X-ray diffraction experiments confirmed that the aggregations of the Cu nanocrystals preferred to grow along (111) direction. In addition, the resulting Cu MDs-modified electrode showed good electrochemical performance as a non-enzyme glucose sensor in alkaline media.     

Adduct of magnesium tetraphenylporphyrin with aniline for colorimetric detection of SO2

Adduct of magnesium tetraphenylporphyrin（MgTPP） with aniline for colorimetric detection of SO₂ was investigated in CH₂C1₂ by steady-state fluorescence and UV-vis absorption spectroscopic techniques.The UV-vis spectra showed that the increasing aniline concentrations resulted in red shift of 3 nm for MgTPP Soret absorption band.Once introduced,SO₂ competes with MgTPP for aniline,which eventually leads to the release of MgTPP and changes in the solution color/absorption.The fluorescence spectra suggested that MgTPP interacted with aniline to form 1:1 molecular adducts,and showed that the binding of MgTPP with aniline with the binding constants of 1.58-1.64 is not only endothermal but entropy-driven withΔH = 1.622 kJ mol^-1, AS = 9.389 J mor^-1 K^-1,and AG = -1.585 kJ mol^-1 at T= 298.15 K.     

第二金属对Co/SiO2加氢催化剂结构和性能的影响（英文）

通过考察Co/SiO2催化剂中活性组分的结构变化及其催化乳酸酯液相氢化反应结果,来研究第二金属添加物对催化剂结构及其催化性能的影响.结果表明,随着金属添加物的加入双金属催化剂中金属Co的表面电子性质以及分散度不断变化,而Co物种颗粒粒径不断减小,因此Co物种和载体SiO2间相互作用不断增强,从而降低Co还原度.乳酸酯氢化反应结果表明,催化剂中活性组分的颗粒大小及其比表面积以及Co物种的还原度和分散度均影响其氢化反应的活性.     

液相色谱-四极杆飞行时间质谱法快速测定草莓中6种植物生长调节剂的残留量

建立了高效液相色谱-四极杆飞行时间串联质谱(HPLC-Q TOF MS)快速检测草莓中2,4-滴、对氯苯氧乙酸、3-吲哚丁酸、氯吡脲、脱落酸、玉米素6种植物生长调节剂的分析方法。样品采用QuEChERS方法(Quick, Easy, Cheap, Effective, Rugged and Safe method)进行前处理(乙腈提取,C18吸附剂净化),采用Eclipse XDB-C8色谱柱(150 mm×4.6 mm, 5 μm),以乙腈-5 mmol/L乙酸铵-0.1%(v/v)甲酸水溶液为流动相,梯度洗脱,Q TOF MS电喷雾负离子模式分析检测。在全扫描采集模式下,以准分子离子峰的峰面积定量,以化合物的精确质量数定性。在Target MS/MS采集模式下,通过碎片离子的精确质量数进一步确证化合物。各化合物在0.005～1.0 mg/L范围内均呈现良好的线性关系,相关系数均大于0.99。6种化合物的检出限为1～5 μg/kg,添加回收率为87%～107%,相对标准偏差(RSD)均小于10%(n=6)。本方法简便快捷,选择性好,灵敏度高,可满足国内外现行法规的限量要求。     

石墨与聚苯乙烯的纳米复合过程研究

石墨具有电导率高、化学稳定性好等优点 ,被广泛应用于聚合物 石墨复合导电材料[1～ 3] .石墨作为聚合物导电填料一般以粉末形态居多 .用粉末状石墨填料往往需要较高的填充量才能得到理想的导电性能 .石墨也可以制备成膨胀石墨 ,将它与聚合物复合 ,可以大幅度降低石墨的填充量 .如一般粉末状石墨填料与聚合物复合制备的导电材料其逾渗阀值为 1 5 %～ 2 0 % ,电导率达到 1 0 -4 ～1 0 -7Ｓ ｃｍ[4 ] ;而若采用膨胀石墨方法 ,逾渗阀值则低于 3% ,电导率可达到 1 0 -2 Ｓ ｃｍ以上[5～ 7] .Ｐａｎ等[7] 报道用膨胀石墨与聚合物复合得到纳米复合…     

Efficient approach to allylated quinolines via palladium-catalyzed cyclization–allylation of 1-azido-2-(2-propynyl) benzenes with allyl methyl carbonate

The palladium-catalyzed cyclization–allylation reaction of ortho-azido propynylbenzenes 1 and allyl methyl carbonate 2d gives the corresponding allylated quinolines in moderate to good yields. The reaction of 1-azido-2-(2-propynyl)benzene 1a proceeds smoothly with 10 mol % Pd(PPh₃)₄ and 5 equiv K₃PO₄ or NaOAc in DMF at 100 °C to afford 3,4-diallylquinoline 3a in 69% yield in the case of R² = H and 3-allylquinoline 4 in 67% yield in the case of R² ≠ H.     

Ultrasound‐assisted dispersive liquid–liquid microextraction coupled with capillary gas chromatography for simultaneous analysis of nine pyrethroids in domestic wastewaters

A simple and rapid ultrasound‐assisted dispersive liquid–liquid microextraction method coupled with GC‐flame ionization detection was developed for simultaneous determination of nine pyrethroids in domestic wastewater samples. An ultrasound‐assisted process was applied to accelerate the formation of the fine cloudy solution using small volume of disperser solvent, which markedly increased the extraction efficiency and reduced the equilibrium time. Various parameters affecting the extraction efficiency were investigated, including the type and volume of extraction solvent and disperser solvent, extraction and ultrasonic time. Good linearity was obtained for all analytes in the range of 0.8–100 μg/L with the correlation coefficient (r²)≥0.998. The recoveries at three spiking levels ranged from 75.3 to 101.2% with the RSD less than 8.7% (n=5). Under the optimum condition, the enrichment factors for the nine pyrethroids ranged from 728‐ to 1725‐fold. This method offered a good alternative for routine analysis due to its simplicity and reliability.     

Ultra‐fast LC–ESI‐MS/MS method for the simultaneous determination of six highly toxic Aconitum alkaloids from Aconiti kusnezoffii radix in rat plasma and its application to a pharmacokinetic study

A fast, sensitive, and efficient ultra‐fast LC–ESI‐MS/MS method was developed for the simultaneous quantitation of six highly toxic Aconitum alkaloids, that is, aconitine, mesaconitine, hypaconitine, benzoylaconine, benzoylmesaconine, and benzoylhypaconine, in rat plasma after oral administration of crude ethanol extracts from Aconiti kusnezoffii radix by ultrasonic extraction, reflux extraction for 1 h, and reflux extraction for 3 h, respectively. The separation of six Aconitum alkaloids and aminopyrine (internal standard) was performed on an InertSustain® C₁₈ column, and the quantification of the analytes was performed on a 4000Q ultra‐fast LC–MS/MS system with turbo ion spray source in the positive ion and multiple‐reaction monitoring mode. Absolute recoveries ranged within 65.06–85.1% for plasma samples. The intra‐ and interday precision and accuracy of analytes were satisfactory. The methods were validated with sensitivity reaching the lower LOQ for aconitine, mesaconitine, hypaconitine, benzoylaconine, benzoylmesaconine, and benzoylhypaconine, which were 0.025, 0.025, 0.050, 0.025, 0.025, and 0.100 ng/mL, respectively. The method was successfully applied to a pharmacokinetic study of six Aconitum alkaloids in rat plasma after oral administration of crude ethanol extracts from the raw root of Aconitum kusnezoffii Reichb. by three different extraction processes.     

3,3a‐Dihydrocyclo­penta­[b]­chromen‐1(2H)‐ones from the reaction of salicylaldehyde and 2‐cyclo­penten‐1‐one

The two title chromene compounds, 3,3a‐dihydrocyclo­penta­[b]chromen‐1(2H)‐one, C₁₆H₁₂O₂, (I), and 2‐(2‐hydroxy­benzyl­idene)‐3,3a‐dihydrocyclo­penta­[b]chromen‐1(2H)‐one, C₁₉H₁₄O₃, (II), have been determined in the monoclinic space group P2₁/n. Compound (I) is mainly stabilized by C—H⋯π inter­actions. Compound (II) is linked into infinite one‐dimensional chains with a C(3) motif via inter­molecular O—H⋯O hydrogen bonds. The inter­molecular C—H⋯π and π–­π inter­actions also play key roles in stabilizing the crystal packing. Two intra­molecular C—H⋯O hydrogen bonds with S(5) motifs were detected in (II).