毛细管电色谱-激发诱导荧光检测动物性食品中多肽类抗生素

以4-氟-7-硝基-2,1,3-苯并呋咱（NBD-F）为荧光试剂,建立了毛细管电色谱-激光诱导荧光（CEC-LIF）检测动物性食品中痕量杆菌肽、多粘菌素B和粘杆菌素等环状多肽抗生素的分析方法。在50 mmol/L的硼酸缓冲液（pH 7.5）中,多肽类抗生素经60℃衍生反应45 min。所得衍生产物采用苯基毛细管色谱填充柱进行分离,流动相为乙腈-磷酸盐缓冲液（pH 5.0,10 mmol/L）（55∶45,v/v）,辅助压力为3.8 MPa,分离电压为-10 kV,流速为0.02 mL/min。结果表明,多肽类抗生素的检出限（S/N=3）为5.0~10.0 ng/mL,满足目标物最大残留限量的检测要求。方法应用于饲料和牛奶样品的分析,平均回收率为72.9%~112.4%。该方法预处理操作简单、灵敏,为动物性食品中兽药残留分离分析提供了新手段。     

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。     

毛细管电泳分离-激光诱导荧光检测生物胺

采用新合成的6-氧-[(1-琥珀酰亚胺)氧酰甲基]-荧光素乙酯(SOFE)作为柱前衍生试剂,毛细管电泳分离-激光诱导荧光检测了乙醇胺(EOA)、组胺(His)、甲胺(MA)、乙胺(EA)、酪胺(TYR)及苯乙胺(PEA)6种生物胺。在硼酸-硼砂缓冲溶液(pH8.5)中,室温(25℃)下衍生10min。用pH8.5的含25mmol/LSDS15%(V/V)乙腈的40mmol/L硼酸盐溶液作为电泳缓冲溶液,6种衍生物在15min内完全分离,检出限在2.5×10-11～8×10-11mol/L之间。该方法应用于酱油中生物胺的测定,结果令人满意。     

4-(6-甲基-2-苯并噻唑偶氮)间苯二酚作螯合剂反相HPLC分离测定V(V)、cu(Ⅱ)、co(Ⅱ)、Ni(Ⅱ)、cr(VI)

本文提出用4-(6-甲基-2-苯并噻唑偶氮)间苯二酚(MBTAR)为柱前衍生试剂,用含有15mmol/L TBA·Br,10mmool/L pH6.0 HAc-NaAc缓冲溶液的甲醇-水(75/25,V/V)混合溶液作流动相,在C_8柱上分离和测定了V(V)、Cu(Ⅱ)、Ni(Ⅱ)、co(Ⅱ)和Cr(Ⅵ)。当信噪比为3时,其检出限为0.15～6.1ppb。本法干扰少,分离时间短,应用于人发分析,结果令人满意。     

柱前衍生化高效液相色谱-荧光检测法测定桑叶中的1-脱氧野尻霉素

采用柱前衍生化高效液相色谱-荧光检测法测定了桑叶中的1-脱氧野尻霉素(DNJ)。用0.05 mol/L HCl提取桑叶中的DNJ,采用6-氨基喹啉基-N-羟基琥珀酰亚氨基甲酸酯(AQC)试剂在pH 8.5硼酸盐缓冲液下对DNJ进行衍生化,以0.02 mol/L磷酸二氢钾缓冲液(pH 5.0)-乙腈(体积比为85∶15)为流动相,利用C18色谱柱(5 μm,250 mm×4.6 mm)分离,在激发波长为250 nm、发射波长为395 nm条件下进行荧光检测,DNJ的AQC衍生物与衍生化试剂的水解产物分离良好。方法的线性范围为0.5～25 mg/L,检出限为0.02 mg/L（S/N=3）。实验测得桑叶中DNJ含量为0.12%;回收率为96.1%～98.6%。     

毛细管电泳-激光诱导荧光法测定人血浆中的富马酸比索洛尔

建立了毛细管电泳-激光诱导荧光检测(CE-LIFD)技术测定人血浆中富马酸比索洛尔含量的新方法。选用荧光素异硫氰酸酯(FITC)为衍生化试剂,当缓冲溶液为25mmol/LNa2B4O7(pH9.2)、分离电压25kV、柱温20℃、电动进样(10kV×8s)、以峰面积内标法定量、于激发波长/发射波长=488/520nm柱上检测时,富马酸比索洛尔得到较好分离。在选定的电泳条件下,对其线性范围(20～1000μg/L)、检出限(10μg/L)、重现性(日内和日间精密度分别小于4.44%和5.59%)和回收率(96.19%～101.80%)进行了测定。结果表明:迁移时间的重现性<1.58%;峰面积之比的重现性<6%。     

NDA柱前衍生毛细管电泳高灵敏安培检测组胺

本文提出了毛细管电泳 2,3 萘二甲醛(NDA)柱前衍生高灵敏安培检测组胺的新方法,对衍生反应条件和电泳分析条件,包括衍生试剂浓度、衍生溶液的pH值、衍生反应时间、分离介质的pH值、进样时间和分离电压进行了优化,确定衍生溶液pH值为9.0,NDA浓度为5.0×10-4mol/L,CN-浓度为2.5×10-3mol/L时的衍生效果最佳;10mmol/LTris H3PO4(pH5.0)为最佳电泳缓冲液,检测电位为0.7V(vs.SCE)时,组胺检出限达6.8×10-8mol/L(S/N=3),较不衍生测定法灵敏度提高6倍,为测定痕量组胺提供了一个新方法。     

基于场放大进样富集的微流控芯片-激光诱导荧光法检测奶制品中的β-酪啡肽

基于微流控芯片-激光诱导荧光分析技术,探讨了奶酪中两种β-酪啡肽(β-CM-5和β-CM-7)的场放大进样富集和检测。采用10 mmol/L硼酸-硼砂溶液(pH8.7)作为衍生缓冲液,5 mmol/L硼砂溶液(pH8.9)作为样品缓冲液,进样10s,60 mmol/L硼砂溶液(pH8.9)作为运行缓冲液,分离电压1500V,在120s内成功分离检测了两种β-酪啡肽。实验结果表明,β-CM-5和β-CM-7的富集倍数是16倍和21倍,检出限分别是8.2 nmol/L和3.6 nmol/L,线性范围分别是0.05~2μmol/L和0.02~1μmol/L,加标回收率在86.9%~107.5%,该方法可应用于奶制品中β-CM-5和β-CM-7的含量测定。     

反相HPLC测定钒、铌、钽的2-(2-吡啶偶氮)-5-二乙氨基苯酚配合物

以2-(2-吡啶偶氮)-5-二乙氨基苯酚(PADAP)为柱前衍生试剂,在含0.1%酒石酸的10mmo1/L(pH3.5)HAc-NaAc缓冲溶液的甲醇/水(50:50,V/V)中(580nm检测),在C₁₈柱上于11min内实现了V、Nb、Ta的同时分离及测定,检出限(S/N=3)为0.34、0.29、7.30ng/mL.该法灵敏度高,用于矿样分析所得结果与推荐值相符,标准加入回收率为99.0%～101.1%.     

4-二甲胺偶氮苯磺酰氯柱前衍生高效液相色谱法测定人体尿液中肌氨酸

建立了以4-二甲胺偶氮苯磺酰氯为柱前衍生试剂的高效液相色谱法测定人体尿液中肌氨酸的含量。通过优化衍生反应的条件,确定了最佳衍生条件为:反应时间20min,反应温度75℃,衍生反应pH为9.8,衍生试剂与肌氨酸比例为4∶1。采用Agilent TC-C18柱(250×4.6mm,5μm),以pH=7.0的9mmol/L磷酸盐缓冲溶液-乙腈(60∶40,V/V)为流动相,流速1.0mL/min,检测波长465nm。结果表明,肌氨酸在0.002~4.00mmol/L范围内呈良好的线性关系,相关系数为0.9998;检测限(S/N=3)为0.70nmol/L;定量限(S/N=10)为2.33nmol/L;加标回收率为95.69%~107.79%。该方法简单、灵敏度高、稳定性好,可用于测定尿液中肌氨酸含量。     

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%.     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.