高效毛细管电泳电导法快速检测复方维生素B片中的VBl、VBl2、VB6和VC

采用高效毛细管电泳电导法同时分离、测定了复方维生素B片中的主要成分VB1，VB12，VB6和VC的含量。研究了运行缓冲溶液的酸度和浓度、电泳电压、进样时间等因素对电泳的影响。在优化的实验条件下：40mmol/L Tris-4mmol/L H3BO3(pH8．0)的缓冲溶液中加入0．30mmol/L CTAB(溴化十六烷基三甲基铵)，分离电压为15kV，上述4组分在5min内得到良好的分离。维生素B1，B12，B6和VC的线性范围分别为5．5～1．0mg/mL；15～1．5mg／mL;1．0～0．40mg／mL和6．6～0．80mg／mL；检测限分别为0．80μg/mL，4．0μg/mL，0．50μg/mL，2．9μg/mL；5次测定峰高的相对标准偏差分别为2．2％，1．6％，3．9％，2．8％。5次测定的平均回收率分别为99％，94％，l00％，97％。     

高效毛细管电泳电导法快速检测复方维生素B片中的VB1、VB12、VB6和VC

采用高效毛细管电泳电导法同时分离、测定了复方维生素B片中的主要成分VB1, VB12,VB6和VC的含量.研究了运行缓冲溶液的酸度和浓度、电泳电压、进样时间等因素对电泳的影响.在优化的实验条件下40 mmol/L Tris -4 mmol/L H3BO3 (pH 8.0) 的缓冲溶液中加入0.30 mmol/L CTAB(溴化十六烷基三甲基铵),分离电压为15 kV,上述4组分在5 min内得到良好的分离.维生素B1,B12,B6和VC的线性范围分别为5.5～1.0 mg/mL; 15～1.5 mg/mL; 1.0～0.40 mg/mL和6.6～0.80 mg/mL; 检测限分别为0.80 μg/mL, 4.0 μg/mL, 0.50 μg/mL, 2.9 μg/mL; 5次测定峰高的相对标准偏差分别为2.2%, 1.6%, 3.9%, 2.8%.5次测定的平均回收率分别为99%, 94%, 100%, 97%.     

毛细管电泳法测定复方芦丁片中的芦丁和维生素C

用毛细管电泳紫外检测法同时测定了复方芦丁片中芦丁和抗坏血酸的含量 ,研究了各种条件的影响 ,得到了优化的实验条件 ,在 30 mmol/L Na2 B4 O7-H3BO3( p H7.5 0 )缓冲溶液中 ,芦丁和维生素 C在 1 3min内得到了良好的分离 ,芦丁和维生素 C分别在 0 .5～ 0 .0 0 5 mg和 5 .0～ 0 .0 5 mg浓度范围内与电泳峰高呈现良好线性关系 ,检测下限分别为 0 .0 0 2 mg和 0 .0 1 mg,应用于实际样品的测定     

复方芦丁片中主要成分的毛细管电泳安培检测

用毛细管电泳安培检测法同时测定了复方芦丁片中芦丁和抗坏血酸的含量 ,研究了各种实验条件对分离效果的影响 ,得到了优化的实验条件。以直径为 5 0 μm的碳纤维微电极为工作电极 ,电极电位为+ 0 .80V(vs.Ag AgCl) ,4 0mmol L的Na2 B4O7 H3 BO3 (pH值为 7 5 0 )为缓冲溶液。在此条件下 ,芦丁和维生素C在 1 0min内得到了良好的分离。芦丁和维生素C分别在 5 .0×1 0 - 8～ 5 .0× 1 0 - 4 g mL、8.0× 1 0 - 8～ 5 .0× 1 0 - 4g mL浓度范围内与电泳峰电流呈现良好的线性关系 ;检测下限分别为 2 .0× 1 0 - 8、5 .0× 1 0 - 8g mL。方法应用于实际样品的测定 ,结果令人满意     

毛细管区带电泳法测定复方芦丁片中芦丁和维生素C的含量

考察了缓冲溶液的pH、背景电解质浓度及分离电压对芦丁、维生素C及苯甲酸分离的影响，建立了以苯甲酸为内标，毛细管区带电泳法快速测定复方芦丁片中芦丁和维生素C含量的新方法。以3g/L硼砂－4g/L硼酸(pH8.18）为运行缓冲液，苯甲酸为内标，在分离电压为25kV，检测波长为254nm的电泳条件下，芦丁、维生素C和内标可在5min实现分离。芦丁的线性方程为：y=2．65x＋0．095（r＝0．9994），线性范围为0．025mg/mL－0．4mg/mL，维生素C的线性方程为：y＝3．1343x＋0．565（r＝0．9991），线性范围0．125mg/mL－1．0mg/mL。方法可用于复方芦丁片的质量控制。     

多壁碳纳米管修饰电极同时测定维生素B2、B6、B12和维生素C

制备了多壁碳纳米管修饰玻碳电极(MWNT/GCE),研究了维生素B2、B6、B12和维生素C共存时在该电极上的电化学行为.实验发现,在HAc-NaAc缓冲溶液中,该电极可同时测定以上四种维生素,线性范围分别为1.0×10-6～1.0×10-4 mol/L、5.0×10-5～2.0×10-3 mol/L、5.0×10-5～7.5×10-4 mol/L和5.0×10-5～2.0×10-3 mol/L,其检出限分别为7.0×10-7 mol/L、1.0×10-5 mol/L、2.5×10-5 mol/L和5.0×10-6 mol/L.样品分析的RSD分别为1.66%、1.71%、2.26%和1.46%.方法简便快捷,可用于四种维生素同时分析测定.     

高效液相色谱柱后化学衍生法测定食品中的VB1及叶酸含量

研究柱后化学衍生荧光检测高效液相色谱分离测定食品中维生素B1和叶酸的方法。采用C18柱,以含有3．5％乙腈的pH5．0磷酸盐缓冲溶液(0．05mol／L)作为流动相反相分离。色谱流出液在柱后与0．4％的过二硫酸钾溶液在线汇合后流经—Teflon管化学反应器时,维生索B1和叶酸转化为强荧光产物,由荧光检测器测定。在最佳条件下,进样20μL,维生素B1和叶酸工作曲线的线性范围分别为0．21～4．2mg／L和0．10～2．0mg／L,峰面积的相对偏差均为2．0％,回收率及实际样品测定结果满意。     

毛细管电泳法测定复方芦丁片的芦丁和维生素C

用毛细管电泳紫外检测法同时测定了复方芦丁片中芦丁和抗坏血酸的含量,研究了各种条件的影响,得到了优化的实验条件,在30mmol/L Na2B2O7-H3BO3(pH7.50)缓冲溶液中,芦丁和维生素C在13min内得到了良好的分离,芦丁和维生素C分别在0.5-0.005mg和5.0-0.05mg浓度范围内与电泳峰高呈现良好线性关系,检测下限分别为0.002mg和0.01mg,应用于实际样品的测定。     

毛细管电泳法分离测定芦丁、槲皮素和连翘苷

用毛细管电泳紫外检测法同时测定了芦丁、槲皮素和连翘苷，研究了各种条件的影响，得到了优化的实验条件，在20mmol/L的Na2B4O7(H3B03调节至pH8．40)-30mmol/L十二烷基硫酸钠-10％乙腈(1 9)的缓冲溶液中，分离电压为12kV时，芦丁、槲皮素和连翘苷在10min内得到了良好的分离，检测波长为254nm，芦丁、槲皮素和连翘苷分别在0．01-1．0mg/mL，0．01-1．0mg／mL和0．05-1．0mg/mL质量浓度范围内与电泳峰高呈现良好线性关系，检测下限分别为0．005mg/mL，0．005mg/mL和0．01mg／mL，应用于实际样品的测定。     

石英芯片电泳分离检测尿中蛋白的研究

通过对缓冲体系、缓冲液浓度、酸度、乳酸钙浓度、乙胺浓度、电泳电压和进样时间的优化选择，用石英芯片电泳一紫外检测法分离了纯人白蛋白和人运铁蛋白；在75mmol／L硼酸盐（pH10．55）（含0．8mmol／L乳酸钙、1％（φ）乙胺）运行缓冲液中，上述两组分在3min内完全分离；纯人白蛋白和人运铁蛋白的线性范围分别为1．0～15．0g/L和1．0～10．0g／L；检出限（S／N=3）均为0．5g／L，应用于临床尿蛋白分离测定，并与Helena琼脂糖凝胶电泳仪电泳结果进行比较，获得一致结果。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Copper catalyzed/mediated synthetic methodology for ebselen and related isoselenazolones

Scope of the copper catalyzed/mediated selenium-nitrogen coupling reaction has been studied for the synthesis of isoselenazolones. It is noticed that the 2-chloro, 2-bromo-, and 2-iodo-aryl amides substrates can be exploited in the selenium-nitrogen coupling reaction by employing 25-100 mol % of CuI/1,10-phenanthroline (L) and potassium carbonate as a base in DMF. Furthermore, electron rich 2-chloro-arylamides also underwent selenium-nitrogen coupling reaction to give biologically important selenium-nitrogen heterocycles. Also, copper-catalyzed selenium-nitrogen coupling reaction has been meticulously applied for the synthesis of diaryl diselenides having methoxy, amine, and amide functionality from respective aryl iodides in the presence of stoichiometric amount of succinimide as an external Se-N coupling partner.     

Knoevenagel condensation catalyzed by novel Nmm-based ionic liquids in water

A series of novel N-methyl morpholine (Nmm) based ionic liquids with 1,2-propanediol group were synthesized and used as catalysts for Knoevenagel condensation at room temperature in water. Under the effect of the catalyst, various aldehydes or aliphatic ketones could react with a wide range of activated methylene compounds well, including malononitrile, alkyl cyanoacetate, cyanoacetamide, β-diketone, barbituric acid, 2-arylacetonitrile and thiazolidinedione. Furthermore, most of the products could be separated just by filtrating and washing with water. Additionally, the catalyst is recyclable and applicable for the large-scale synthesis.     

Construction of polyheterocyclic spirotetrahydrothiophene derivatives via sulfa-Michael/aldol cascade reaction

A series of polyheterocyclic spirotetrahydrothiophene derivatives were obtained in moderate to excellent yields via a catalyst-free sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 under mild conditions. We also present the first asymmetric sulfa-Michael/aldol cascade reaction of chalcones 1 and commercially available 1,4-dithiane-2,5-diol 2 with moderate to good enantioselectivities catalyzed by readily available chiral phase-transfer catalysts (PTCs).     

Suzuki-Miyaura reactions of the soluble guanylate cyclase inhibitor NS2028: a non-product specific route to C-8 substituted analogues

Both soluble guanylate cyclase (sGC) inhibitors ODQ 1 and NS2028 2 are synthesized via improved protocols. In the former case treating 3,4-dihydroquinoxalin-2(1H)-one oxime 8, which can be prepared in two steps from 1,2-benzenediamine, with 1,1′-carbonyldiimidazole (CDI) gives the dihydro-ODQ 10 that in the presence of KMnO₄ oxidises to give ODQ 1 in an overall yield of 46% starting from 1,2-benzenediamine. In the latter case, the synthesis affords NS2028 2 from 2-amino-4-bromophenol 3 in three steps with an overall yield of 85% and avoids the need for chromatography. Furthermore, Suzuki-Miyaura reaction conditions are described that enable the preparation of 8-aryl and 8-heteroaryl derivatives of NS2028 directly from NS2028 2. Finally, demethylation of the 8-(methoxyphenyl) substituted analogues afforded the 8-(hydroxyphenyl) derivatives 40-42. All new products are fully characterised.