对肼基苯磺酸在糖的毛细管电泳衍生中的应用——柱前衍生法

提出利用对肼基苯磺酸作为糖的衍生试剂,以实现快速的毛细管电泳分离与检测.详细研究了影响衍生反应的诸多因素以及衍生产物的毛细管电泳分离条件.结果表明,本方法可以在温和条件下实现快速反应(10min),200nm紫外检测下葡萄糖的最低检出量可达17.6fmol,检出浓度3.6μmol/L.在100mmol/LH₃BO₃(pH=10.24)体系中实现了9种单糖和二糖的高效分离.     

毛细管电泳发光二极管诱导荧光对免疫球蛋白G的检测

采用自行设计、组装的毛细管电泳光导纤维发光二极管诱导荧光检测装置,建立了一种直接测定免疫球蛋白G(IgG)的方法。以蓝色发光二极管(LED)为荧光检测器的激发光源,荧光素异硫氰酸酯(FITC)为柱前衍生试剂,采用毛细管区带电泳,以20 mmol/L硼砂缓冲溶液(pH9.2)为背景电解液进行分离检测。通过对衍生反应条件和电泳分离条件进行优化,确定了最佳实验条件,在该条件下,IgG的线性范围为4.5×10-8~1.2×10-6g/L,检出限为2.0×10-8g/L。该方法简单、高效、选择性好,无需前处理,可用于人血清中IgG含量的测定。     

毛细管电泳柱后衍生激光诱导荧光测定动物组织中卡那霉素类抗生素

采用毛细管电泳柱后衍生激光诱导荧光测定3种卡那霉素类抗生素。研究了在反向电渗流条件下HAc-NaAc缓冲液酸度和浓度对卡那霉素类抗生素分离的影响,研究了Na2B4O7缓冲体系和柱后衍生试剂萘二醛/2-巯基乙醇浓度对检测信号的影响。采用50 mmol/L HAc-NaAc(pH5.0) 0.5 mmol/L CTMAB溶液为分离缓冲液,样品在-15 kV下分离,与柱后衍生试剂1.0 mmol/L NDA 8.0 mmol/L 2-ME 35 mmol/LNa2B4O7(pH10.0)的30%(V/V)甲醇溶液反应,激发诱导荧光检测卡那霉素类抗生素检出限为3.6×10-5~5.2×10-5g/L;本方法用于动物组织中卡那霉素类抗生素残留检测,相对标准偏差小于7.2%;回收率为90.2%~95.3%(n=4)。     

芯片毛细管电泳分离多种FITC衍生的氨基酸

用芯片毛细管电泳激光诱导荧光检测系统研究了分离多种荧光素异硫氰酸酯(FITC)衍生氨基酸的实验条件.采用以乙醇为有机添加剂的胶束毛细管电动色谱分离体系(50 mmol/LSDS,体积分数为15%的乙醇,5 mmol/L pH 9.2的硼砂缓冲液),在72 mm长的通道上实现了10种常见氨基酸的分离,一次分离的时间小于5 min.     

微流控芯片毛细管电泳柱后衍生激光诱导荧光检测氨基酸

建立了微流控芯片毛细管柱后扩散衍生激光诱导荧光检测氨基酸的方法。利用微流控芯片的二维平面结构特征,在分离通道末端增加支通道,通过扩散法引入柱后衍生试剂,避免了电压引入法对分离通道流型的影响,因而提高了分离效率。考察了支通道长度、衍生试剂液面高度、检测点位置对衍生结果的最优条件,考察了衍生试剂引入方法、催化剂种类、缓冲溶液种类对检测结果的影响。用20 mmol/L硼砂-NaOH(pH=10)溶液作为电泳缓冲溶液,与柱后衍生试剂1.0 mmol/L NDA+8.0 mmol/L 2-ME+35 mmol/L硼砂(pH 10.0)的30%(V/V)甲醇溶液反应,精氨酸、苯丙氨酸、天冬酰胺、脯氨酸、丙氨酸、甘氨酸在不加任何添加剂的情况下可达到基线分离。本法用于板蓝根药材中主要游离氨基酸的分离检测,相对标准偏差小于4.4%(n=5),回收率为92.3%~98.6%。所测板蓝根药材中精氨酸和脯氨酸含量分别为14.97,8.02 mg/g。     

毛细管电泳-激光诱导荧光检测法测定卡托普利和N-乙酰-L-半胱氨酸

建立了一种高效、快速的毛细管电泳分离-激光诱导荧光(CE-LIF)检测卡托普利(CAP)和N-乙酰-L-半胱氨酸(NAC)的分析方法。采用1,3,5,7-四甲基-8-溴甲基-二氟二硼-二吡咯甲川(TMMB-Br)为柱前衍生试剂,在50 mmol/L磷酸盐缓冲溶液(pH=8.5)中,40℃下进行衍生反应10min。以荧光素为内标,25mmol/L硼酸盐缓冲溶液(pH=9.5)为电泳背景电解质,14min内达到基线分离。CAP和NAC的检出限分别为0.65nmol/L、0.76nmol/L。将该方法应用于人体尿液和血清中这两种物质的测定,回收率在97.0%~105.7%之间。     

毛细管电泳法分析藏红花植物细胞多糖中单糖组成

以对甲氧基苯胺为衍生试剂,采用毛细管电泳法分析了藏红花植物细胞多糖中的单糖组成。对衍生条件进行了优化,并对毛细管分离条件进行了系统的研究。衍生反应在醋酸含量9.5%(v/v)、80 ℃下反应2 h的衍生产率最大,衍生产物紫外检测波长234 nm。在优化的毛细管电泳分离条件(未涂层熔融石英毛细管柱(60 cm(有效长度50 cm)×50 μm),柱温25 ℃,电压20 kV,使用350 mmol/L硼酸电解液(pH 10.21),压力(3.4475 kPa)进样5 s)下,基线分离了11种结构相近的醛糖(来苏糖、木糖、核糖、葡萄糖、甘露糖、半乳糖、鼠李糖、纤维二糖、麦芽糖、乳糖)、酮糖(果糖)的衍生产物。应用该方法定量检测了藏红花植物细胞多糖水解物中糖的成分,各糖的回收率为94.3%～105.4%,相对标准偏差为3.3%～4.6%。     

新型柱前衍生试剂对甲氧基苯磺酰氟用于氨基酸毛细管电泳分离

大多数氨基酸不含有芳香环等生色团,在紫外可见光区无吸收,无法直接用紫外和荧光法检测,因此将氨基酸衍生为具有较强紫外或荧光吸收的衍生物进行检测是常用的分析方法.本实验采用常温下能与氨基酸快速反应的对甲氧基苯磺酰氟(MOBS-F)为新型柱前衍生试剂,建立了毛细管电泳分离常见的20种氨基酸的方法.     

新型衍生试剂柱前衍生氨基酸的高效液相色谱分析

以邻硝基苯磺酰氯为标记试剂,RP-HPLC为分析模式,建立了一种新的氨基酸衍生化方法.通过液质联用对产物进行定性,研究并确定了最佳衍生化条件:衍生温度25 ℃,缓冲液pH9.0,衍生时间10 min.实验建立了20种氨基酸的HPLC分离方法:选用Kromasil C18柱,流动相A为30 mmol/L的NH4Ac溶液(pH 7.5),B相为乙腈;采用梯度洗脱,检测波长275 nm,室温.20种氨基酸在0.025 ～6.4 mmol/L范围内线性关系良好,相关系数在0.998 0 ～0.999 8之间,检出限为0.01 ～0.113 nmol.     

氨基酸衍生物在毛细管区带电泳下的分离研究

采用新合成的荧光试剂咔唑-9-乙基氯甲酸酯作为柱前衍生试剂,利用毛细管区带电泳法对衍生氨基酸进行分离,考察了该试剂用于毛细管区带电泳法进行氨基酸分离的关键条件,实现了12种氨基酸的快速基线分离.     

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.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

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.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

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.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.     

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.