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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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邻苯二甲醛-尿素柱前衍生高效液相色谱法快速检测枸杞中牛磺酸 总被引:8,自引:0,他引:8
干枸杞经粉碎、匀浆、离心后,通过阳离子交换柱脱去样品中其它氨基酸,再通过Zorbax-C8柱进行柱前衍生分离。衍生剂:A.4%OPA甲醇溶液;B.尿素∶磷酸钠盐缓冲液(pH6.8)=1∶3(W/V)。流动相:甲醇∶0.01mol/L乙酸钠溶液(pH6.8)=35∶65(V/V)。紫外检测波长330nm。牛磺酸浓度在0.1~1.0mmol/L范围内可被定量测定。回收率可达100.31%±1.98%,变异系数(CV)为1.94%。 相似文献
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高效液相色谱法测定环境水中痕量4,4′-二氨基联苯、4-硝基酚和苯酚 总被引:2,自引:0,他引:2
采用PhenomenexSpherexC18色谱柱,以含50mmol/L乙酸-乙酸钠缓冲溶液(pH6.0)的V(乙腈)∶V(乙醚)∶V(水)=12∶10∶78混合溶液为流动相,用分光光度法检测,检测波长为275nm,在16min内实现了4,4′-二氨基联苯、4-硝基酚和苯酚的同时分离测定。检测限分别为0.14,0.19和0.08ng。标准回收率分别为98.85%,98.15%和98.10%。方法灵敏度高,用于环境水样分析时结果令人满意。 相似文献
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反相高效液相色谱法测定杜仲中的松脂醇二葡萄糖甙 总被引:6,自引:0,他引:6
建立一种测定杜仲中松脂醇二葡萄糖甙的反相高效液相色谱法。杜仲粉末的甲醇提取液经大孔树脂柱处理后,在YWG-C18柱上进行HPLC分析。流动相为28%(V/V)的甲醇水溶液;流速1.0mL/min;紫外检测波长232nm。方法平均回收率为99.22%(n=3),变异系数0.50%~0.74%(n=5)。进样量在0.068μg~0.68μg范围内线性关系良好,r=0.9999。所建立的方法可作为评定杜仲及杜仲制品降压效果的一种简便、快速和准确的测定方法。 相似文献
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An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions. 相似文献
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An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction. 相似文献
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The Diels-Alder reactivity of 1,2-heteroborines (H4C4B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed. 相似文献
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Xi-Liu YunWen-Ying Bi Jian-Hui HuangYu Liu Daisy Zhang-NegrerieYun-Fei Du Kang Zhao 《Tetrahedron letters》2012,53(38):5076-5080
A variety of N-aryl and N-alkyl carbazolones were conveniently achieved in good to high yields via Pd2(dba)3-mediated intramolecular coupling of N-substituted α-iodo enaminones under microwave irradiation. The Pd(0)-catalyzed cyclization was found to proceed favorably with the more electron-deficient phenyl ring during the reactions involving unsymmetrical N,N-diaryl α-iodo enaminones. This unique property enables the construction of carbazolone skeleton containing nitro substituted benzenoid ring. 相似文献
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Both substituted 2,4,5,6-tetrahydrocyclopenta[c]pyrazoles and 2,4,5,6-tetrahydropyrrolo[3,4-c]pyrazoles have been synthesized by the 3+2 intramolecular dipolar cycloaddition of nitrilimines to alkynes. This cyclization has been extended to more versatile 3-bromo derivatives by the use of alkynylbromides as dipolarophiles. 相似文献
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An efficient and benign method for the preparation of aminomethyl-substituted fullerenes has been developed. The process, involving catalyst free, visible-light irradiation of 10% EtOH-toluene solutions containing fullerene C60 and N-trimethylsilylmethyl-substituted amines by using a 20 W compact fluorescent lamp, leads to formation of aminomethyl-substituted fullerene adducts in a highly efficient manner. The photoaddition reaction takes place via a pathway initiated by visible light absorption by C60, followed by SET from the amine to the triplet excited state of C60. Ethanol-promoted desilylation of the resulting a minimum radical then generates the corresponding α-amino radical which couples with the C60 radical anion to form the anion precursor of the fullerene adducts. The new approach using visible-light takes place under mild conditions and it does not require the use of photocatalysts. Thus, the method developed in this effort could broadens the range of functionalized fullerene derivatives that can be readily prepared. 相似文献
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Viktor A. Dmitriev Mariia M. Efremova Alexander S. Novikov Vladimir V. Zarubaev Alexander V. Slita Anastasia V. Galochkina Galina L. Starova Andrey V. Ivanov Alexander P. Molchanov 《Tetrahedron letters》2018,59(24):2327-2331
The reactions of various nitrones with indolyl- and pyrrolylacrylates proceeds regioselectively with high diastereoselectivity in the case of aldonitrones, and represents an effective method for obtaining new indolyl- and pyrrolyl-substituted isoxazolidine carboxylates stabilized by weak (CH?O) and moderate (NH?N) strength intramolecular hydrogen bonding. The resulting cycloadducts exhibit promising in vitro anti-influenza activities. 相似文献
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A transition metal-free method for the direct amination of benzoxazoles using formamides as nitrogen sources is reported, which was mediated by an inexpensive and environmentally friendly tetrabutylammonium iodide/tert-butyl hydroperoxide system and gave the 2-aminobenzoxazole derivatives with moderate to good yields. 相似文献
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Multifunctionalized 1,2,3,4-tetrahydropyridines are concisely synthesized in good yields via l-proline-catalyzed or l-proline/FeCl3-cocatalyzed one-pot multicomponent reactions (MCRs). The MCRs involve a domino hydroamination/prins reaction/Mannich-type reaction/intramolecular dehydration-cyclization process. The molecular structure of 5baa, one of multifunctionalized 1,2,3,4-tetrahydropyridines, was confirmed by single-crystal X-ray diffraction. 相似文献
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Yin Shuhui Liu Hongping Zhang Jianyang Jiang Bo Wang Li Sha Guohe Lou Nanquan 《化学物理学报(中文版)》2003,16(1):3-8
The multi-photon dissociative photoionization dynamics of CF3I has been studied with femtosecond two-color pump-probe time of flight mass spectra at a pump pulse of 265 nm and a probe pulse of 398 nm. The life constants of CF3I+ and its fragment ions CF3+ and I+ are obtained as (96±7), (198±130) and (167±6)fs, respectively. The multi-photon dynamics leading to these ions differ. CF3I+ corresponds to a (1+2′) transition with one-photon pump excitation to the A band of CF3I. CF3+ are mainly formed by a tow-photon probe excitation to the CF3+ with subsequent dissociation of parent ions. I+ are produced in (2+2′) combined with (1+1′+2′) process. The results provide information on the multi-photon pathways involved. 相似文献