The NHCs-mediated cross-coupling of aromatic aldehydes with benzyl halides: synthesis of α-aryl ketones

A new NHCs-mediated synthetic method was found to produce α-aryl ketones in 22-63% yields in one-pot process from the corresponding aromatic aldehydes and benzyl halides. This method is the first example of the NHCs-mediated intermolecular nucleophilic acylation of aromatic aldehydes with benzyl halides.     

HPLC study of tissue distribution of loganin in rats

A rapid, sensitive and selective high performance liquid chromatography (HPLC) method was developed and validated for determination of loganin in rat tissues. Samples were prepared based on a simple protein precipitation. Separation of loganin was achieved on a reversed-phase C(18) column (250 x 4.6 mm, 5 microm) with a mobile phase consisting of acetonitrile and water (16:84, v/v) at a flow rate of 1.0 mL/min. The detection wavelength was set at 236 nm and the temperature of the column was kept at 30 degrees C. The method was applied to study tissue distribution of loganin in rats after a single administration of loganin at a dose of 20 mg/kg. The highest level was observed in kidney, then in stomach, lung and small intestine. The lowest level was found in brain. The peak levels were attained at 90 min in most tissues. It was indicated that kidney was the major distribution tissue of loganin in rats, and that loganin had difficulty in crossing the blood-brain barrier. It was also found there was no long-term accumulation of loganin in rat tissues.     

高效液相色谱梯度法测定雷公藤制剂中雷公藤甲素的含量

采用高效液相色谱梯度法分离测定雷公藤制剂中雷公藤甲素的含量,用国产YWG色谱柱分离,二极管阵列检测器检测,所得三维光谱与空白光谱进行差减,取波长218nm处色谱图积分,定量。与等度法比较,梯度法具有更高的分离度、灵敏度,测定雷公藤口服液中雷公藤甲素的质量浓度为202．0μg／L,每片雷公藤片剂含甲素11．74μg,结果显著低于等度法和标示量（P<0．05）。     

头发微量元素及钙含量测定的应用价值评价

以125例2～5岁儿童为对象，测定其全血和头发铅、锌、铁、钙含量；以全血铅、锌、铁、钙含量为标准，应用诊断试验评价方法评价头发铅、锌、铁、钙测定的应用价值。结果表明，头发铅测定的灵敏度可达88．3％，应用串联试验，头发铅测定的特异度可提高至81．8％，阳性预测值达69．6％，阴性预测值达78．8％。头发锌测定的灵敏度可达86．1％，特异度为52．4％，阳性预测值75．6％，阴性预测值为68．8％。头发铁测定的灵敏度为72．0％，特异度为77．5％，阳性预测值为83．6％，阴性预测值为63．3％，头发钙测定的灵敏度为78．9％，特异度为69．1％，阳性预测值为69．8％，阴性预测值为78．4％。锌缺乏、铁缺乏、钙缺乏，或铅负荷过高，或数种微量元素缺乏及铅中毒并存是当前严重影响儿童健康成长的常见原因。运用现代检测技术早期发现微量元素缺乏及铅中毒患儿并及时采取防治措施对促进儿童正常生长发育至关重要。头发样品容易采集、运送和保存，因此头发微量元素含量测定适合在中小城镇及农村使用。但其应用价值应进行科学评价。     

有机颜料与表面活性剂DBS混合物的光催化降解

以TiO₂为光催化剂,研究了表面活性剂十二烷基苯磺酸钠(DBS)和有机颜料耐晒大红BBN(BBN)为混合组分的光催化降解,结果表明,pH值、底物的用量对体系的降解有显著影响,在碱性条件下,DBS的降解速率相对较快,而在酸性环境时,颜料的降解较快,在TiO₂等电点时,降解最慢,酸性条件下, TiO₂对BBN和DBS的吸附性比在碱性和中性环境中大,BBN/DBS体系中, DBS增大了BBN的水溶性,但是没有明显提高BBN的降解褪色速度,DBS浓度为0.42 g/L时,颜料降解最快,0.042 g/L时次之,2.1 g/L时最低,在BBN降解过程中DBS自身也被降解,且略有促进作用。     

Dissolution and bioavailability of phenobarbital in solid dispersion with phosphatidylcholine.

The dissolution of phenobarbital (PB) from solid dispersion with phosphatidylcholine (PC) was studied. PB was present in an amorphous state in solid dispersion (PB-PC) if the mole fraction of PB was under 0.75. Thus, supersaturation was observed when an excess amount of PB-PC was dispersed in pH 1.2 and 6.8 media. The degree of supersaturation was largest when the mole fraction of PB was 0.25, although it was only 1.3-fold of the PB solubility in this case. Dissolution from PB-PC was rapid and complete in both pH 1.2 and 6.8 media regardless of the mole fraction of PB, above 90% within 5 min. Bioavailability after the oral administration of PB-PC to rabbits with a dose of 15 mg/kg equivalent to PB was compared with that of PB crystals. The area under the plasma concentration curve was bigger, but not significant. The maximum concentration was significantly higher, and the time to maximum concentration was significantly faster. These results indicate that the absorption rate became high with PB-PC because the dissolution was rapid.     

柱后衍生HPLC法测定功能饮料中的牛磺酸

建立柱后衍生–高效液相色谱法测定功能性饮料中牛磺酸的含量。功能性饮料中的牛磺酸经水溶提取后与邻苯二甲醛柱后衍生,以柠檬酸三钠溶液(p H 3.2)为流动相,用AMINO–NA色谱柱分离,荧光检测器检测,激发波长为338 nm,发射波长为425 nm,柱后衍生反应温度为55℃,流量为0.4 m L/min。牛磺酸质量浓度在5.0~25.0μg/m L范围内与色谱峰面积线性关系良好,r=0.999 8,检出限(S/N=3)为0.11μg/m L,测定结果的相对标准偏差为0.73%(n=6),加标回收率在99.2%~101.6%之间。该方法灵敏度高、选择性好,可用于市售功能性饮料中牛磺酸的测定。     

Ag-Sn合金的氧化过程与热力学性质

采用密度泛函微扰理论(DFPT)计算了Ag-Sn-O体系中O原子在Ag-Sn合金中的运动与反应, 及该体系中几种化合物的结合能、生成焓以及热容与自由能随温度的变化. 计算发现O原子存在于Ag晶格的四面体间隙, 若存在八面体间隙会使体系能量升高288.23 kJ·mol-1; Sn则在Ag晶格中主要以置换形式存在. 计算得到结合能大小顺序为Ag6O2>SnO2>Ag2SnO3>SnO>Ag2O. SnO2的稳定性最高, 生成焓约-591.1 kJ·mol-1, SnO是一种过渡相, 而Ag2SnO3和Ag6O2为亚稳相, 都能在常温下存在, 这与相关实验结果一致. 原子间相互作用曲线说明Sn—O的成键能力明显高于Ag—O, 氧化时只会形成Sn—O键. 准谐函数近似计算(QHA)表明Ag2SnO3的热容远高于其它化合物, 其德拜温度约500 K, 升温能力仅为SnO2的1/3, 可有效解决AgSnO2电接触材料中温升过快的问题, 而布居分布和Gibbs自由能则进一步说明SnO2是Ag-Sn-O体系中最稳定的相.     

Extraction and separation of cationic surfactants from river sediments: application to a spectrophotometric determination of cationic surfactant in an aquatic environment using membrane filters.

The quantitative extraction of cationic surfactant (CS+) in river sediments was studied. Further, the developed method was applied to the spectrophotometric determination of CS+ in urban river sediment samples by solid-phase extraction with membranes. A mixture of methanol and hydrochloric acid was proposed as an eluent. Dried sediment was digested in the eluent under ultrasonic irradiation. After elution, the eluent was evaporated to almost dryness. The residue was dissolved in a small volume of methanol and diluted to a certain volume with water. The pH of the solution was adjusted to 4-5 to separate iron and some other metals as precipitates of hydroxides. The solution was passed through two-piled membranes: first glass-fiber and then polytetrafluoroethylene (PTFE) membranes. A small volume of methanol was passed through the membranes to elute any CS+ retaining on the membranes. After passing the methanol solution through a cationic exchange resin column, the retained CS+ was eluted with methanol containing a high concentration of sodium chloride. Water, Bromophenol Blue (BPB) and hydrochloric acid were added to the solution. The solution was passed through a mixed cellulose ester membrane filter to retain an ion associate of CS+.BPB-. The retained ion associate was dissolved in a small volume of N,N-dimethylformamide together with the membrane filter, followed by the addition of triethanolamine to make the solution alkaline. The absorbance due to BPB2- was measured at 603 nm against a reagent blank. This method was applied to the determination of CS+ in river water and sediment. A cationic surfactant in sediments at 10(-5) mol kg-1 levels was detected with satisfactory precision. It was found that CS+ was about 500-fold enriched in the sediment from water at the place where domestic wastewater was discharged.     

纳米催化剂在CO_(2)加氢制甲醇中的研究进展北大核心CSCD

为减缓温室效应,将CO_(2)转换成高附加值的甲醇是减少CO_(2)排放的有效途径,而高效催化剂是CO_(2)加氢制甲醇反应规模化的关键.可调控合成的具有量子尺寸效应的纳米催化剂在该反应上具有独特的优势.因此我们深入探讨了反应机理,综述了纳米材料在CO_(2)加氢制甲醇中的研究进展,最后给出了高效催化剂可能的发展方向.     

高频感应炉燃烧–红外吸收法测定银杏及银杏叶中的硫含量

采用高频感应炉燃烧–红外吸收法测定银杏叶、银杏果肉、银杏壳和银杏仁中的硫含量。样品以艾士卡试剂为熔融剂,在800℃马弗炉内熔融1 h,冷却后测定硫含量。硫的质量分数在0.40%~4.00%范围内与吸收峰面积呈良好的线性关系,线性相关系数为0.990 4,检出限为0.000 9%。测定结果的相对标准偏差为4.04%(n=11),平均加标回收率为101.03%。将红外吸收法与电感耦合等离子体原子发射光谱法及硫酸钡重量法进行比对试验,3种方法测定结果相一致。利用该方法测定了不同区域银杏叶中硫的含量,结果表明,风景区和居民区银杏叶干燥基全硫的含量较低,重工业区硫含量较高。对同一地区的银杏果肉、银杏壳、银杏仁中干燥基全硫的含量进行比较,结果表明银杏果肉硫含量最高,银杏壳次之,银杏仁最低。该方法灵敏度高,重现性好,可用于银杏及银杏叶中硫含量的准确测定。     

阴离子表面活性剂聚二硫二丙烷磺酸钠的合成

利用硫化钠与硫磺反应制备二硫化钠,然后将二硫化钠与1,3-丙磺酸内酯反应,合成了一种可作为电镀添加剂的阴离子表面活性剂——聚二硫二丙烷磺酸钠(SPS)。采用核磁共振氢谱对合成产物进行结构表征,确认了产物结构及产率。通过正交试验研究了产物产率与反应物配比、反应温度、溶剂加入量等因素之间的关系,找出了最优合成条件:第一步合成二硫化钠的反应中,硫化钠/硫磺物质的量比为1∶1.3,温度55℃,加水量18 mL;第二步合成SPS的反应中,1,3-丙磺酸内酯/硫化钠物质的量比为1.7∶1,温度40℃,溶剂量75 mL,产物的最高产率可达到95.8%。     

A New Capillary Electrophoresis Apparatus with Piezoelectric Ceramics High Voltage Source and Amperometric Detector

IntroductionHighperformancecapiliar}'electrophoresis(HPCE)isanewanalyticaltechnology'rapidly'developedinrecentyears.Withtheadvantagesofsmallsample.highsensitivity,highresolution.rapidanalysisandverycheaprunning,ithasbeenappliedinchemistry'.lifescienc...     

亲水相互作用色谱柱串联C18柱高效分析饮品中的胭脂红

建立了亲水相互作用色谱柱(HILIC)串联C18柱的方法,高效分离实际样品中的胭脂红,并对色谱柱的串联顺序以及色谱分离条件进行优化。结果表明:当HILIC柱在前C18柱在后,流动相为乙腈-乙酸铵(5 mmol/L)=91∶9(V/V),流速为0.9 mL/min,柱温为25℃,检测波长为508 nm时,此时胭脂红的分离效果最佳。在最佳的色谱分离条件下,选用两种市售饮品进行实际样品的测定,回收率在81.2%~119%。方法适用于水相样品中的强极性物质的高效分离与分析。     

火焰原子吸收分光光度法测定维血康颗粒中总铁

建立火焰原子吸收分光光度法测定维血康颗粒中总铁的含量,火焰类型选择空气–乙炔,测定波长为248.3 nm,测定时间为4.0 s,燃气流量为0.9 L/min,以氘灯作为背景校正。铁的质量浓度在2.4~28.8μg/mL范围内与吸光度呈良好的线性,线性相关系数r~2=0.999 8。6次测定结果的相对标准偏差小于1.0%,样品加样回收率为93.89%,方法检出限为0.011 3μg/mL。该方法具有准确度高,稳定性、重复性好等优点,可用于维血康颗粒中总铁含量的测定。     

Electro-responsive polyacrylamide-grafted-gum ghatti copolymer for transdermal drug delivery application

An application of polyacrylamide-grafted-gum ghatti (PAAm-g-GGH) copolymer for transdermal delivery of an anti-psychotic drug, quetiapine fumerate triggered by electric stimulus was explored. The electro-responsive PAAm-g-GGH was prepared by free radical polymerization underneath nitrogen atmosphere subsequent to alkaline hydrolysis. The PAAm-g-GGH was used as drug reservoir gel and crosslinked films of GGH and PVA as rate controlling membranes (RCM). The reservoir gels were uniform and translucent; pH of gels was 6.56–7.06, which is in the pH range of skin and drug content was from 89.57% to 94.51%. The thickness of RCMs was 163–227?μ; thickness was increased with increased glutaraldehyde concentration and all the RCMs were permeable to water vapors. When electric stimulus was absent, a small amount of drug was permeated from the formulations, while drug conveyance was enhanced in the existence of stimulus. Drug permeation was increased with increase in electric stimulus from 2 to 8?mA. Over two fold increase in flux was observed after application of electric stimulus. Under “on–off” electric stimulus, faster drug permeation was seen under ‘on’ condition and permeation was decreased when stimulus was ‘off.’ Histopathology study confirmed reversible alteration of skin structure under electric stimulus.     

聚环氧乙烷凝聚重量法结合ICP–AES法测定玻璃中的二氧化硅

建立聚环氧乙烷凝聚重量法结合电感耦合等离子体发射光谱法(ICP–AES)法测定玻璃中二氧化硅的分析方法。玻璃试样经1 000℃高温下无水碳酸钠熔融,以盐酸浸出后蒸成湿盐状,再用聚环氧乙烷凝聚,过滤并将沉淀灼烧,然后用氢氟酸处理,其前后的质量差即为沉淀的二氧化硅量,滤液中的二氧化硅用ICP–AES法测定,两者相加得试样中二氧化硅的总含量。在选定的条件下,用ICP–AES法测定二氧化硅的线性范围为0.20~50μg/m L,线性相关系数为0.999 5,检出限为0.20μg/m L。测定结果的相对标准偏差为0.45%(n=6),方法的回收率在98.6%~101.9%之间。该方法具有较高的准确度和良好的精密度,测定速度快,可用于玻璃中二氧化硅含量的测定。     

Cationic Emulsion Polymerization of Octamethylcyclotetrasiloxane (D4) in Mixtures with Alkoxysilanes

The cationic emulsion polymerization of octamethylcyclotetrasiloxane (D4) in mixtures with methyltriethoxysilane (MTES) and vinyltriethoxysilane (VTES) was studied by FTIR ATR, GC, the development of a toluene insoluble fraction of the polymer and a gravimetric analysis. The polymerization of D4 alone was also conducted for comparison and, additionally, the development of molecular weight of polydimethylsiloxane (PDMS) obtained in that process was studied by GPC. Dodecylbenzenesulphonic acid (DBSA) was used as a surfactant and catalyst. The process was carried out in a “starved feed” mode by adding dropwise the monomer mixture to the aqueous solution of DBSA. FTIR ATR spectra were recorded by the sensor placed in the probe tip of a ReactIR 15^TM apparatus. It was found that the silicone polymer formation proceeded faster when D4 was polymerized in the mixture with alkoxysilanes, especially in the beginning of the process, and that already at the beginning of the process, the partly crosslinked polymer was formed. The induction period of ca. 30 min was observed and the concentration of cyclic siloxanes (D4 and decamethylcyclopentasiloxane—D5) remained at a very low level in the course of the reaction and only traces were detected in the final product. The particle size development in the course of the reaction was also studied and it was found that the particle size distribution was bimodal and was broadening as the reaction proceeded, though this phenomenon was less distinct when D4 was polymerized in the mixtures with alkoxysilanes. The structure of the reaction product was confirmed by ²⁹Si NMR.     

动态超声辅助萃取与HPLC联用测定淫羊藿中黄酮类化合物

建立了动态超声辅助萃取与高效液相色谱在线联用系统,用于测量淫羊藿中黄酮类化合物。萃取过程在一个循环体系中完成,萃取完成后,通过采样环采集20μL萃取液,萃取液被流动相载入色谱系统进行分离检测。4种黄酮类化合物用HPLC–MS区分,通过比较色谱峰面积选择优化萃取条件。选择50℃的水浴温度,50%的乙醇作为萃取剂,萃取剂流速为1.5 mL/min,萃取时间为8 min,样品量为15 mg。用该法测量淫羊藿样品中4种黄酮类化合物,日内、日间精密度分别为1.05%～2.05%,0.30%～3.63%(n=6)。淫羊藿中的主要化合物淫羊藿苷的加标回收率为95.2%。该方法可用于测量淫羊藿中的黄酮类化合物。     

Sensitive determination of melatonin by precolumn derivatization and reversed-phase high-performance liquid chromatography

A sensitive determination method for melatonin was developed. Melatonin was derivatized under alkaline conditions in the presence of hydrogen peroxide. The resultant fluorophore was excited at 247 nm and the emission wavelength was 384 nm. The Stokes shift was 137 nm, which was longer than that of melatonin itself (lambda ex 280 nm, lambda em 330 nm). The melatonin derivative was separated by reversed-phase HPLC in about 15 min and the calibration curve was linear from 500 amol to 5 pmol (r > 0.999) with the detection limit of 500 amol (S/N = 5). The sensitivity of this method was about ten times higher than that of previous methods. Both the day-to-day precision and within-day precision were about 5%, and the derivative of melatonin in the aqueous solution was stable for more than 10 days. This method was successfully applied to the determination of melatonin in rat pineal gland.