共查询到20条相似文献,搜索用时 171 毫秒
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《分析化学》1982,(12)
研究报告期页码 1) 6)11)16)21)26)65)70)74)82)87)91)129)134)138)1土3)1凌8)r、了吐、了.、‘r、矛‘、了吸、了官、J‘、了胜、护叮‘了、了叮、了‘、了胜、了.、(了‘1 1111122222233333152)193)196)199)204)210)214)257)262)267)矛矛几、矛r‘、矛.、‘r、了仁、尹t、J‘‘、fl‘、了几、几口44 4 4 4 4 la 55(272)(277)(281)(321)5弓56、.了、.2、、工、声‘1户、.,了、,产、.产、、了、.夕连0 4 8 2 la一匕吮jg六工J32 33 33 33 34 38 58 39 3940产.、夕‘.、了,、产亨.、护口气矛亨‘了.、产.、沙f、了.、6 6 6 6 6 7 7t了777 8 … 相似文献
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碳60的发现是荣获了1996年诺贝尔化学奖的重大贡献,将我们带进了又一个化学新世界。实践中碳60分了的独特构型引起了中学化学教师和学生的极大兴趣,但尚缺少其分了模型的简易制作方法。作者在教学过程中创造了一种碳60分了模型的制作方法。 相似文献
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自20世纪初期,德国化学家EmilFischer首先合成了甘氨酸二肽片段,并第一次提出“peptide”(多肽)这一名词,多肽化学的研究已经历了100多年的发展.1953年,Vigneand小组首次完成了生物活性肽催产素的合成,并因此于1955年获得了诺贝尔化学奖.1963年,Merrifield提出了多肽固相合成法,并发明了第一台多肽自动合成仪,大大简化了多肽合成的流程、提高了合成的效率,从而促使多肽化学实现了飞跃式发展,Merrifield也因此获得了1984年诺贝尔化学奖.1965年,我国科学家完成了牛结晶胰岛素的合成, 相似文献
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β—环糊精和α—萘乙酸包络物的荧光光谱研究 总被引:5,自引:0,他引:5
本文研究了水溶液中β-环糊精和α-萘乙酸包络反应,研究了包络物的荧光光谱性质,测定了包络物的形成常数,讨论了各种水溶性一元醇对该包络物形成及荧光性质的影响,并对其应用了作了预测。 相似文献
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乙酰乙酸乙酯-BR化学振荡反应的研究 总被引:2,自引:0,他引:2
本文首次报道了乙酰乙酸乙酯-IO-3-H2O2-Mn2+-H2SO4体系的化学振荡反应。研究了各种因素对振荡反应的影响,测定了最佳反应条件及振荡反应的浓度范围。研究了温度变化对振荡反应的影响,并计算了振荡反应的表观活化能,对振荡反应产物进行了分析,并测定了体系主要反应的计量关系,采用UV法对金属离子的作用和催化机理作了研究,探索了BR反应中I2的产生机理及消耗机理,对体系中有关反应物的作用作了说明。在FKN机理的基础上,对BR反应的自催化反应步骤和控制机理进行了初步的探索,并对有关实验现象作了说明。 相似文献
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This study demonstrates the analysis of cimetidine in human plasma with HPLC using a simplified sample preparation by protein precipitation with perchloric acid. Plasma cimetidine concentration was determined by plotting peak height ratio of cimetidine to ranitidine (internal standard, IS) against cimetidine concentrations in plasma. The cimetidine and ranitidine peaks were completely separated and no interference from plasma was observed. The lower limit of quantification (LLOQ) of the method was established at 0.1 microg/mL with a precision of 4.3% and a relative error of 1.9%. The average analytical recovery was >90% over the range of cimetidine concentrations (0.1-15.0 microg/mL). The linearity of calibration curve was excellent (r(2) > 0.999). The within- and between-day precision and accuracy, expressed as the coefficients of variation and relative error, were found to be less than 5%. Compared with previously reported methods, the analytical technique for cimetidine determination in human plasma presented here demonstrates comparable accuracy and precision, an acceptable analysis time, shorter and simpler sample preparation, and a reduced need for complicated equipment. The method presented here is simple and rapid, and the precision and sensitivity are appropriate for the determination of cimetidine in plasma in pharmacokinetic studies. 相似文献
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建立以核磁共振技术测定片剂中西咪替丁含量的方法。采用Agilent DD2-500型核磁共振波谱仪,以氘代甲醇为溶剂、对苯二甲酸二甲酯为内标,测试温度25℃,弛豫时间为20 s,脉冲角为45°,采集时间为2 s,扫描次数为16次,采集核磁共振氢谱。该方法线性范围为0.1~5.0 mg/mL,相关系数r=0.999 8,测定结果的相对标准偏差为0.11%(n=6),平均加标回收率在100.03%~100.58%之间。用该方法测定不同厂家片剂中西咪替丁的含量,测定结果与药典方法相吻合。该方法简单快速、样品用量少,适用于西咪替丁的质量控制。 相似文献
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K Xu V K Arora A K Chaudhary R B Cotton I A Blair 《Biomedical chromatography : BMC》1999,13(7):455-461
A quantitative method was developed and validated for rapid and sensitive analysis of cimetidine in human plasma. The method involved the use of liquid chromatography (LC) coupled with atmospheric pressure chemical ionization (APCI) and selected reaction monitoring (SRM) mass spectrometry (MS). A cimetidine analog, SKF92374, was used as the internal standard. Separation of cimetidine and the internal standard was accomplished using a reverse-phase HPLC column (C18). The eluted components were ionized by the APCI source and subsequently detected by a highly selective triple quadrupole mass spectrometer in the SRM mode. Linear standard curves were obtained from 5 ng/mL (lower limit of quantitation) to 10,000 ng/mL. The results demonstrated excellent precision (%RSD 1. 1-8.9%) and accuracy (94.7-108.0%) over this range. In addition, the amount of plasma sample needed for analysis was small (50 muL), and the plasma pretreatment (analyte recovery >94%) was simple and time saving. This assay was used to evaluate cimetidine levels in premature infants following intravenous infusion of cimetidine. 相似文献
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Determination of cimetidine and related impurities in pharmaceutical formulations by high-performance liquid chromatography. 总被引:1,自引:0,他引:1
The analytical characteristics of cimetidine tablets were studied. A high-performance liquid chromatographic method was developed in order to assay cimetidine and its related impurities simultaneously. A reversed-phase system and diode-array detector were used. 相似文献
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The electrochemical reduction of cimetidine, an H2-antagonist of histamine used in the treatment of duodenal and gastric ulcers, has been examined by using a variety of electrochemical techniques. Reduction in 0.1. M HCl occurs at ?0.8 to ?1.1 V vs. SCE depending on the experimental conditions. Square-wave and cyclic voltammetry were found to be the best techniques for the determination of cimetidine whereas sampled-d.c., normal pulse, and differential pulse polarography were not useful. The detection limit for the determination depends on the condition employed but can be as low as 1 ng ml?1 (4 nM). A linear calibration plot is obtained up to 2 μg ml?1 and calibration curves can be used at higher concentrations. The high sensitivity is due to reactant adsorption. The electrode process appears to involve a 4-electron reduction of the cyano group in cimetidine. The major metabolites of cimetidine can also be determined by this method. 相似文献
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G. L. Perpétuo D. A. Gálico R. A. Fugita R. A. E. Castro M. E. S. Eusébio O. Treu-Filho A. C. M. Silva G. Bannach 《Journal of Thermal Analysis and Calorimetry》2013,111(3):2019-2028
Thermogravimetry (TG), differential scanning calorimetry (DSC), polarized light thermal microscopy (PLTM), as well as X-ray powder diffraction (XRD) and Fourier transformed infrared spectroscopy (FTIR) were used to study the thermal behavior and the chemical structure of cimetidine, famotidine, ranitidine-HCl, and nizatidine. The TG–DSC curves show that the famotidine and ranitidine-HCl suffer decomposition during melting and they are thermally less stable in comparison with cimetidine and nizatidine, the latter being the most stable of all the drugs studied in this study. The DSC curves of famotidine and ranitidine-HCl show exothermic peaks immediately after the melting, confirming the occurrence of thermal decomposition. The DSC curves also show that the cimetidine and nizatidine have some thermal stability after melting. The thermal events shown in the PLTM images are consistent with the results shown in the TG–DSC and DSC curves. The XRD patterns show that the cimetidine and famotidine are less crystalline compared with ranitidine-HCl and nizatidine. The theoretical FTIR bands are in agreement with those obtained experimentally, and in some cases, no difference is observed between the theoretical and experimental values, even being identical in one of the cases. 相似文献
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Cimetidine reacting with 1,5-dichloroanthraquinone in acetone solution can produce a charge-transfer complex that shows a strong absorption peak at 343 nm. The absorption value at 343 nm increased with cimetidine concentration in the range of 0.01—0.5 μg/mL, with regression coefficient of 0.9995 and detection limit of 0.006 μg/mL. This simple and sensitive method has been successfully applied to determine cimetidine in tablets and capsules, with average recovery of (98.47±0.92)% and (97.07±1.16)%, respectively. Furthermore, the mole ratio of the complex between cimetidine and 1,5-dichloroanthraquinone is 2∶1, and the mechanism of charge-transfer reaction is explored. 相似文献
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Ho TS Reubsaet JL Anthonsen HS Pedersen-Bjergaard S Rasmussen KE 《Journal of chromatography. A》2005,1072(1):29-36
Recently, we demonstrated for the first time liquid-phase microextraction (LPME) of polar drugs based on carrier mediated transport. In this new extraction technique, selected analytes were extracted as ion-pairs from small volumes of biological samples, through a thin layer of a water immiscible organic solvent immobilised in the pores of a porous hollow fibre (liquid membrane), and into a microl volume of an acidic aqueous acceptor solution placed inside the lumen of the hollow fibre. In the current paper, this new extraction technique was combined with liquid chromatography-mass spectrometry (LC-MS) for the first time. Carrier mediated LPME was evaluated for several new model drugs (0.01 相似文献
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Grewia gum is a naturally occurring polysaccharide which has potential as a pharmaceutical excipient. Differential scanning
calorimetry and Fourier transform infrared (FT-IR) spectroscopy techniques were used to examine the thermal and molecular
behaviours, respectively, of mixtures of grewia gum with cimetidine, ibuprofen or standard excipients, to assess potential
interactions. No disappearance or broadening of the melting endotherm was seen with cimetidine or ibuprofen. Similarly, there
was no interaction between grewia gum and the standard excipients tested. The results obtained using thermal analyses were
supported by FT-IR analysis of the material mixtures. Grewia gum is an inert natural polymer which can be used alone or in
combination with other excipients in the formulation of pharmaceutical dosage forms. 相似文献