三重比光谱导数法同时测定氨基酸注射液中的三种芳香氨基酸

采用三重-比光谱导数分光光度法同时测定氨基酸注射液中的3种芳香氨基酸,讨论了测定酪氨酸、苯丙氨酸和色氨酸的实验条件.实验结果表明,在pH 7.4的NaH2PO4-NaOH缓冲溶液中,3种氨基酸的线性范围分别为:酪氨酸2.0×10-6～2.8×10-5 mol/L,苯丙氨酸2.0×10-5 ～1.6×10-3 mol/L,色氨酸4.0×10-7～1.6×10-6 mol/L.回收率在95%～105%之间.     

红珍珠血脂康胶囊的营养成分分析

对红珍珠血脂康胶囊一般营养成分、氨基酸、维生素及矿物质元素进行了测定和营养学评价．结果表明：红珍珠血脂康胶囊在配料组成上具有天然、营养成分全面等特点．其中氨基酸成分全面，蛋白质与脂肪酸的含量分别为7.23％、10％，VC高达180mg/100g，Ca、Zn、Fe、P的含量分别为4109．0mg／kg、160．6mg／kg、494．5mg／kg、1194．3mg/kg为进一步研究提供了基础数据．     

柱后衍生-荧光检测高效液相色谱法快速测定鲜牛奶中链霉素残留量

牛奶样品经磷酸溶液提取，提取液用苯磺酸阳离子交换柱和C18固相萃取柱净化，链霉素残留液用甲醇从C18固相萃取柱上洗脱，经旋转蒸发器减压蒸干，残渣用0．01mol／L庚烷磺酸钠溶液溶解，用柱后衍生-高效液相色谱荧光检测器在激发波长263nm和发射波长435nm测定．方法线性范围为0.01～0．10mg／kg；在0．01～0．10mg／kg范围，三个添加水平的回收率为78．3％～80．2％，变异系数(CV)为7．4％～12．4％，方法检出限为0．005mg／kg．     

离子色谱法测定氯化石蜡中的总氯量

采用氧瓶燃烧法处理氯化石蜡样品,用离子色谱测定吸收液中Cl^-的方法来确定氯化石蜡的总氯量。在Metrosep A SUPP5型阴离子分离柱上,以3．2mmol／LNa2CO3和1．0mmol／LNaHCO3混合溶液作为淋洗液,抑制型电导检测,检出限为0．87μg／L,线性范围0．1—4mg／L,相对标准偏差与回收率分别为1．71％～2．14％、94．4％-103．1％。该方法简便、快速,结果与国家标准法比较无显著性差异。     

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％。     

多元校正紫外光度法同时测定甲硝唑与维生素B6

本文报道多元校正紫外光度法同时测定甲硝唑和维生素B6。首先在0．1mol／LHCl溶液中对甲硝唑和维生素B6两组分混合溶液进行分光光度法测定,然后将所得的重叠光谱数据经计算机采集后,分别用化学计量学方法中的偏最小二乘法（PLS）和主成分回归法（PCR）进行处理,并用于药物样品的测定,获得了较好的定量分析结果。该法甲硝唑和维生素B6的线性范围分别为1．0～28．0mg／L和1．0～28．0mg／L,检出限分别为0．568mg／L和0．364mg／L。     

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。     

一种能直接染色鉴定氨基酸的薄层展开剂及其应用

1　实验部分1.1　主要仪器和试剂　　薄层色谱设备,微量加样器。所用试剂均为分析纯。20种合成蛋白质的氨基酸单标准对照液的质量浓度均为10g/L。其中,半胱氨酸先用2mol/L盐酸溶解;酪氨酸、色氨酸先用0 25mol/LNaOH溶解,然后再分别以蒸馏水稀释;其余氨基酸都用10mmol/LNaOH作溶剂。标准混合对照液由对应的10g/L的氨基酸单标准液等体积混合而成。显色液:质量浓度为7g/L的茚三酮乙醇溶液。1.2　样品处理　　按常规方法制备醇溶蛋白、谷蛋白、牛血清白蛋白、鱼精蛋白、酪蛋白等5种碱解的氨基酸供试液;羽毛粉经发酵微生物释放的蛋白酶水解…     

溴取代紫外分光光度法同时测定痕量色氨酸和酪氨酸

研究了在水和乙醇溶液中Br2与色氨酸和酪氨酸发生的取代反应,利用测定反应前后Br2与KI反应生成I2的量,建立了不经分离同时测定色氨酸、酪氨酸的新方法。用I2在水和乙醇水溶液中对紫外光的吸收不同和加和原理,建立联立方程并分别求得各自的含量。方法测定色氨酸和酪氨酸的线性范围分别为0.0～0.90mg·L-1和0.0～1.00mg·L-1,表观摩尔吸光系数(ε)在水溶液中分别为1.65×105、1.71×105 L.mol-1.cm-1;在乙醇水溶液中分别为2.31×105、2.05×105 L.mol-1.cm-1。用该法对复合氨基酸溶液和鸡蛋清中色氨酸和酪氨酸进行测定,相对标准偏差分别为1.8%、1.2%,回收率为96.0%～104.3%。     

双波长K系数法同时测定食品中山梨酸和苯甲酸

本文采用双波长K系数法同时测定食品中山梨酸和苯甲酸。山梨酸和苯甲酸的线性范围分别为0～10mg／L、0～40mg／L；样品测定的精密度分别为1．3％～3．7％和1．4％～4．4％；样品加标回收率分别为96．3％～98．7％和96％～102．2％。本法快速、简便、可靠。     

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.     

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.     

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.     

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.     

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.