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嘌呤类生物碱基的反相高效液相色谱分离及饮料中咖啡因的测定 总被引:4,自引:0,他引:4
本文报道了在SpherisorbC18柱上,以甲醇-KH2PO4-Na2PO4缓冲溶液(pH8.2)作流动相,同时分离和测定黄嘌呤,鸟嘌呤,腺嘌呤,茶碱和咖啡因,并用于饮料中咖啡因子的测定,检出限为μg/L级。标准加入回收率在95.6~105.0%。 相似文献
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苦荞叶片中芸香甙的薄层色谱定量研究 总被引:1,自引:0,他引:1
根据芸香甙的理化性质,建立了一种测定植物样品中芸香甙含量的薄层紫外扫描法,采用硅胶GF254薄层板,样品经甲醇提取浓缩后点样,展开剂为乙酸乙酯-甲酸-水(8+1+1)。用薄层色谱扫描仪在波长355nm处测定芸香甙的吸收强度并直接定量。该法操作简便,灵敏度高,定量准确,结果稳定,应用于苦荞叶片中芸香甙含量测定,得到良好结果,线性范围为0~2.0μg/μL,斑点的最低检出限为5.0ng,回收率102% 相似文献
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生物碱基的反相离子对色谱分离及茶叶中咖啡因测定的研究 总被引:2,自引:0,他引:2
报道了在YWGC18柱上,以甲醇+水(7.5+92.5)、含5mmol/LpH5.0磷酸盐缓冲溶液、10mmol/LTBA·Br作流动相,同时分离尿嘧啶、9N二羟丙基腺嘌呤、腺嘌呤、可可碱、尿嘧啶丙酸、9N二羟丙基茶碱和咖啡因,并用于茶叶中咖啡因的测定,检出限为μg/L级,标准加入回收率为95.3%~105.0%。 相似文献
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用线性扫描伏安法(ISV)、微分脉冲伏安法(DPV)和循环伏安法(CV)在玻碳电极 (GCE)上研究了麦地霉素(MD)在不同介质中的阳极伏安行为。发现在0.1mol/L Na_2HPO_4溶 液中于0.75V(υs. Ag/AgCl)左右产生一个阳极氧化峰,峰高与MD浓度5 × 10~(-5)~1×10~-1g/L 范围内呈线性关系。用本法不需分离直接测定了药物制剂和加标尿样。RSD为1.8%(n= 10)。尿样中MD的回收率为95%~115%。实验结果表明MD的电极氧化反应为不可逆过 程。 相似文献
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催化动力学光度法测定痕量钒(V)的研究 总被引:6,自引:2,他引:6
研究了在pH9.2的硼矽介质中,痕量钒(V)催化H2O2氧化桑色素褪色反应体系的新催化光度法,测定范围为0~7.5μg/50mL,加标回收率为95%~98.5%,测定2μg钒(V)RSD为1.68%,用于水样中痕量钒(V)的测定。 相似文献
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毛细管气相色谱法测定速效伤风胶囊中对乙酰氨基酚、咖啡因、马来酸氯苯那敏的含量 总被引:3,自引:0,他引:3
用5%Ph-Me-Silicone毛细管色谱柱,FID,二阶程序升温,以正十六烷作为内标物测定速效伤风胶囊中对乙酰氨基酚、咖啡因、马来酸氯苯那敏的含量。浓度线性范围:对乙酰氨基酚4~20g/L,咖啡因0.084~0.42g/L,马来酸氯苯那敏0.15~0.75g/L。平均回收率(n=5):对乙酰氨基酚99.62%(RSD=0.44%)咖啡因96.46%(RSD=1.32%),马来酸氯苯那敏98.55%(RSD=0.65%)。 相似文献
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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%. 相似文献
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Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction
Laurent Gavara Thomas Boisse Jean-Pierre Hénichart Adam Daïch Philippe Gautret 《Tetrahedron》2010,66(38):7544-5571
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. 相似文献
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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. 相似文献
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Rebecca J. Burton Mandy L. CrowtherNeal J. Fazakerley Shaun M. FilleryBarry M. Hayter Jason G. KettleCaroline A. McMillan Paula PerkinsPeter Robins Peter M. SmithEmma J. Williams Gail L. Wrigley 《Tetrahedron letters》2013
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. 相似文献
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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. 相似文献
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N. A. Nedolya 《Chemistry of Heterocyclic Compounds》2008,44(10):1165-1219
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. 相似文献
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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. 相似文献
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《Tetrahedron》2014,70(21):3377-3384
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. 相似文献
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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. 相似文献