用高效液相色谱法快速测定甜菊糖甙

本文用高效液相色谱法快速分离甜菊糖甙的四种成份的方法,并测定了几种甜菊饮料制品中这四种糖甙及其中糖类的含量。色谱条件为:μ-Bondapak NH_2柱,柱前加Bondapak AX/Corasil(4×22mm)预柱;乙腈:0.02M(NH_4)_2HPO_4水溶液(75:25)作流动相,流速为2.0ml/min;示差折光检测(RI)。所有样品都须用乙腈:水(75:25)溶解,才能保证有良好的分离效果。     

高效液相色谱法同时测定饮料中的糖类、甜味剂及防腐剂

利用Waters244型高效液相色谱仪的两套分开的系统(A和B),可同时在十八分钟内定量测定饮料中的糖类、甜菊甙的三种异构体、糖精钠、苯甲酸和山梨酸等十一种组分。A系统:C_(10)键合相柱,HAc/NaAc饱和水溶液/H_2O=10/1/89,2.0ml/min,紫外254nm检测,用于测定糖精钠扣两种防腐剂。B系统:氨基键合相柱,CH_3CN/0.02M(NH_4)_2HPO_4水溶液=75/25,2.0ml/min。示差折光检测。用于测定糖类和甜菊甙。以外标校正峰高法定量。各组分的相对标准偏差在2%左右,用标准添加法验证各组分的回收率在90%～108%之间。测定了十八种液体和固体饮料中上述成分的含量。     

高效液相色谱法同时测定丹参提取物中4种成分的含量

建立反相高效液相色谱法同时测定丹参醇提物和超临界提取物中原儿茶醛、丹酚酸B、隐丹参酮和丹参酮ⅡA含量的方法.采用RP-HPLC梯度洗脱的方法进行测定,色谱条件为:Agilent C18柱(5 μm,4.6×250 mm);以1%醋酸乙腈-1%醋酸水为流动相进行梯度洗脱;检测波长:0～25 min (280 nm),25～60 min (270 nm);流速0.5 mL/min;柱温:35 ℃.测定了丹参醇提取及超临界提取物中以上4种成分的含量;4种成分线性关系均良好(r>0.9995),平均加样回收率均大于95.0%,RSD均小于3.0%.该方法一次进样,可以同时测定丹参中水溶性成分原儿茶醛和丹酚酸B、脂溶性成分隐丹参酮和丹参酮ⅡA的含量.     

高效液相色谱法测定保健食品中的大豆异黄酮

建立了一种测定保健食品中大豆异黄酮的高效液相色谱分析方法,该方法可以使常见的大豆异黄酮6种主要成分大豆甙、黄豆甙、染料木甙、大豆甙元、黄豆黄素、染料木素得以分离和检测。采用乙腈-磷酸水溶液(pH2.8)作流动相,梯度洗脱,Venusil MP-C18色谱柱(150 mm×4.6 mmi.d.,5μm),流速为1.0 mL/min,紫外检测器,检测波长254 nm。结果表明各组分线性关系良好,相关系数R2为0.9991~0.9998,加标回收率在87%~106.9%,相对标准偏差均小于2%。检出限0.25~0.48μg/mL,该方法可同时测定大豆异黄酮的6种成分。     

高效液相色谱法分离和测定甜菊甙

〕本文研究了应用反相高效液相色谱法分离甜菊糖甙,对其中主要成分甜菊甙进行了鉴定和定量测定。分析条件如下：柱,YWG-C18H37;流动相,甲醇-水（75:25,体积／体积）;紫外检测波长205nm,甜菊甙最小检知量：0.2μg。分析了18个甜菊糖甙样品,定量测定结果：甜菊甙含量在43.80～60.39%,相对标准偏差为1.6%。     

高效液相色谱法测定红葡萄酒中白藜芦醇的四种异构体

将红葡萄酒用β-葡萄糖苷酶水解处理,使其中的白藜芦醇甙转换成白藜芦醇。采用高效液相色谱法测定水解前后顺、反式白藜芦醇含量的变化,从而计算出葡萄酒中白藜芦醇的4种异构体的含量。色谱柱为Symmetry C18柱(3.9 mm i.d.×150 mm),流动相为乙醇-0.05%乙酸水溶液(体积比为23∶77),紫外检测波长为306 nm。实验结果表明:白藜芦醇的4种异构体在其质量浓度为0.2~50.0 mg/L时均有良好的线性关系(r>0.999),白藜芦醇及其甙的顺、反异构体的最小检出量分别为:0.81     

工业制备高效液相色谱法制备淫羊藿中的黄酮系列对照品

淫羊藿甙和朝藿定A、B、C是淫羊藿中重要的活性成分,本研究应用工业制备高效液相色谱从淫羊藿粗提物中分离制备了这4个成分。淫羊藿粗提物经大孔吸附树脂粗分离获得相应的组分后,利用工业制备高效液相色谱完成精制纯化。采用自装填Chromatorex C18制备柱(220 mm×77 mm, 10 μm),乙腈-水(26:74或30:70, v/v)为流动相进行洗脱,在35 min内,实现了这4种成分的基线分离及规模制备。从300 g粗提物(总黄酮含量约20%)中获得淫羊藿甙33 g、朝藿定C 4.6 g、朝藿定B 3.7 g和朝藿定A 0.6 g,产品纯度均达到98%以上。此方法通过两步分离即可实现这4种成分的完全分离,具有快速高效、产品纯度高的特点,适于淫羊藿中淫羊藿甙、朝藿定A、B、C系列对照品的规模制备。     

大豆中蛋白质含量的示波滴定

1 引言大豆中蛋白质含量的测定,国内外标准方法是采用凯达尔法,作者研究了用示波滴定的方法进行测定,样品用H_2SO_4-Na_2SO_4-CuSO_4消化处理,N以NH_4~+的形式存在于试液中.在pH5～6用四苯硼钠(Na-TPB)沉淀NH_4~+,过量的TPB,在pH10～12的NaOH-NaAc碱性底液中有明显的示波图,用四乙基氯化铵标准溶液反滴定至TPB示波图下切口突然消失为终点,据此计算出N含量,再换算为蛋白质的含量.2 实验部分2.1 仪器与试剂 LS-1A型示波滴定仪(山东电讯七厂);磁力搅拌器;钨电极;汞膜电极;PHS-3C型酸度计.N标准溶液:1.000×10~3mg/L,用优级纯NH_4CI配制;Na-TPB溶液:0.05mol/L;30%NaOH溶液;无水Na_2SO_4;CuSO_4-5H_2O;H_2SO_4相对密度1.84g/ml;HAc-NaAc缓冲溶液:pH=5.5,取2mol/LNaAc溶液,滴加HAc调节,用酸度计测量;四乙基氯化铵标准溶液:0.02mol/L,用示波滴定法标定.     

差示紫外光度法测定氯锇酸铵的纯度

研究了(NH_4)_2OsCl_6及共存离子的紫外吸收光谱。在369nm波长处(NH_4)_2OsCl_6有一个稳定的吸收峰,其摩尔吸光系数为7.6×10~3,在很宽的浓度范围内服从比尔定律。将试样简单地溶于0.5mol/L HCl溶液中即可进行差示光度测定。试样含量为99％时,方法的变异系数小于0.09％。本文确证了影响光谱纯氯锇铵纯度的主要杂质为NH_4Cl,并给出了氯锇酸铵标准的标定方法。     

高钛渣中TiO_2及TiC的快速相分析

拟定了高钛渣中快速测定TiO_2及TiC相分析的方法。将第一称样完全溶解于HNO_3-H_3PO_4中,在H_2SO_4-HCl-(NH_4)_2SO_4介质中用铝还原钛成三价,重铬酸钾滴至中性红蓝色终点为TiO_2+TiC的含量,第二称样控制温度<280℃仅溶于H_3PO_4,余法同前,测得结果为TiO_2含量。差减后得TiC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.     

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.