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人参挥发油的提取和分析 总被引:7,自引:0,他引:7
应用GC-MS-DS联机分析人参挥发油是当前较好的方法,但人参挥发油的提取方法和GC-MS条件的选择明显影响人参挥发油这一复杂天然混合物的分离和鉴定。本工作严格控制提取条件,提高了挥发油收率,达0.95%;选择最佳GC-MS条件,鉴定出76种化合物,该法稳定重现性好。 相似文献
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天然和人工培植红景天挥发油的对比研究 总被引:2,自引:0,他引:2
应用GC-MS和GC-IR两种联机法对比研究了天然和人工培植红景天挥发油、分别鉴定出27个和24个化合物。MS给出结构信息和IR给出官能团信息相结合,提高了分析测试复杂样品的可靠性。 相似文献
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聚酯型聚氨酯样品用基体辅助激光裂解离子化质谱(MALDI-TOF/MS)和热裂解色谱质谱(PYGC/MS)方法进行了鉴定,PYGC/MS方法可检出PU的一些组成单元的化学结构,但PYGC/MS中大多数的峰,无法从常规的标准化合物的质谱数据库中检索到,而MALDI-MS方法,可明确测出PU试样各种单元的组合、聚合度及PU长链的序列分布,质量数范围可达2300。 相似文献
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建立了用GC-MS(SIM)内标定量法快速测定人尿中可待因及其代谢物浓度的方法,样品经酸水解、乙醚/异丙醇提取,用MSTFA-MBTFA衍生化后进样于GC-MSD,方法灵敏、准确,可用于监测吸毒者尿中可待因,吗啡类药物的浓度。本法已经受IOC的1992年水平考试的考验。 相似文献
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ICP—MS分析人血清中微量元素 总被引:2,自引:0,他引:2
用ICP-MS分析人血清中22种元素,为克服基体抑制效应,采用内标元素Sc和In分别校正质量数80以下和80以上元素的测定,获得满意的结果,通过对牛血清标准物质的测定,检验分析结果的准确性和方法的可靠性。 相似文献
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ICP-MS分析人血清中微量元素 总被引:2,自引:0,他引:2
用ICP-MS分析人血清中22种元素。为克服基体抑制效应。采用内标元素Sc和In分别校正质量数80以下和80以上元素的测定,获得满意的结果。通过对牛血清标准物质的测定,检验分析结果的准确性和方法的可靠性。 相似文献
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两步法提取笼内金属富勒烯 总被引:3,自引:0,他引:3
两步法提取笼内金属富勒烯郝春雁,刘子阳,徐文国,郭兴华,刘淑莹(中国科学院长春应用化学研究所,吉林大学化学系,长春,130022)关键词金属富勒烯,索氏提取,DEI-MS,LDI-MS目前笼内包含金属的富勒烯化合物以其新颖独特的结构和性质而格外引人注... 相似文献
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糖的基质辅助激光解吸/电离质谱(MALDI—MS)研究 总被引:1,自引:0,他引:1
通过糖类化合物3种常用基质MALDI-MS分析效果的比较以及寡糖和多糖正,负离子MALDI-MS谱的对比,找到了适合糖分析的基础2,5-DHB,探讨了糖类化合物激光解吸/电离条件下形成离子的过程,指出了Na^+,K^+离子在寡糖分子量测定的重要作用,借助柱层析分离手段,成功地测出分子量大于10000的葡聚糖的分子量。 相似文献
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依据中药大黄的近红外光谱信息,采用最小二乘双胞胎支持向量机( LSTSVM)算法,通过MATLAB软件编程,建立参数可优化识别模型,实现了对中药大黄的真伪鉴别.将实验材料98个大黄样品随机划分为训练集和测试集,对于训练集60个样品采用留1/5法交叉验证优化模型参数,以所选最优化参数结合训练集样品的近红外光谱建立最优识别模型,对测试集的38个样品的真伪迸行识别,识别率可达97.4%.结果表明,LSTSVM算法是一种有效的识别方法,可依据中药大黄的近红外光谱对其真伪进行快速识别.同时,本研究将大黄样品6次随机划分为训练集和测试集,建模预测平均识别率为93.4%,表明采用LSTSVM算法建立识别模型具有较好的稳健性. 相似文献
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When used for physiologic fluid analysis, shifts in retention times, even at constant flow rates, can cause integrators to function inadequately as tools for peak identification and thus result in concentration errors. A system capable of data collection, identification, quantification, and long-term storage that primarily uses retention times only for identification of elution sequence is described. Operator identification, aided by manipulation of x and y coordinates of the chromatograph, enhances positive identification of compounds for the experienced chromatographer. 相似文献
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Potential agents for biological attacks include both microorganisms and toxins. In mass spectrometry (MS), rapid identification of potential bioagents is achieved by detecting the masses of unique biomarkers, correlated to each agent. Currently, proteins are the most reliable biomarkers for detection and characterization of both microorganisms and toxins, and MS-based proteomics is particularly well suited for biodefense applications. Confident identification of an organism can be achieved by top-down proteomics following identification of individual protein biomarkers from their tandem mass spectra. In bottom-up proteomics, rapid digestion of intact protein biomarkers is again followed by MS/MS to provide unambiguous bioagent identification and characterization. Bioinformatics obviates the need for culturing and rigorous control of experimental variables to create and use MS fingerprint libraries for various classes of bioweapons. For specific applications, MS methods, instruments and algorithms have also been developed for identification based on biomarkers other than proteins and peptides. 相似文献
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B. L. Milman Yu. Yu. Ilyasov N. V. Lugovkina A. A. Golovina A. V. Dmitriev 《Journal of Analytical Chemistry》2017,72(13):1280-1288
A new approach to the identification of microorganisms is presented. It includes the transformation of their MALDI mass spectra aimed at reducing mass scale by one order of magnitude and the use of standard software for building mass spectral libraries of low-molecular compounds and library searches. A library of 728 transformed (“rescaled”) mass spectra of 182 strains for some Streptococcus species was built. With this library, the rate of true microorganism identification was estimated by cross-comparison between library mass spectra (internal validation of the approach). The true identification rate was 84% for three Streptococcus species, which corresponds to the average trueness of species identification by MALDI as found in the literature. The proposed approach to identification can be considered as a method of choice for solving identification problems under consideration. 相似文献
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Target identification is an important step in drug discovery, and computer-aided drug target identification methods are attracting more attention compared with traditional drug target identification methods, which are time-consuming and costly. Computer-aided drug target identification methods can greatly reduce the searching scope of experimental targets and associated costs by identifying the diseases-related targets and their binding sites and evaluating the druggability of the predicted active sites for clinical trials. In this review, we introduce the principles of computer-based active site identification methods, including the identification of binding sites and assessment of druggability. We provide some guidelines for selecting methods for the identification of binding sites and assessment of druggability. In addition, we list the databases and tools commonly used with these methods, present examples of individual and combined applications, and compare the methods and tools. Finally, we discuss the challenges and limitations of binding site identification and druggability assessment at the current stage and provide some recommendations and future perspectives. 相似文献
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After an explanation of the theoretical basis of exchange reactions between soluble and difficultly soluble electrolytes, their advantages and disadvantages as analytical test reactions were illustrated by the following examples: 1. identification of oxalatc and fluoride by their reaction with calcium carbonate; 2. identification of sulfate and chromatc with barium carbonate; 3. identification of phosphate and chromate with lead carbonate; 4. identification of the halogens with silver carbonate; 5. identification of bromide and iodide with .silver thiocyanatc; 6. identification of bromide with silver thiocyanatc and photodecomposition; 7. identification of phosphate and oxalate with lead iodate; 8. identification of the halogens with silver iodate.The mechanism of these reactions is discussed and a hypothesis formulated to explain why ion exchange ensues, even if the concentration of the reagents is smaller than would be necessary for mass precipitation. Many of the reactions described arc not listed in jacouson's Encyclopedia of Chemical Reactions. 相似文献
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At present, mass spectrometry (MS) is the most reliable method for identification but there is not yet a quantitative equation describing this fact. In this investigation an approach to the quantitative assessment of the reliability of identification by MS is proposed which is useful for determination of the selectivity and the validation of analytical methods. Mass spectra of the analytes are presented as maps in which the characteristic ions and their intensities are used for identification. A formula for the quantitative expression of the significance of these parameters to the reliability and the identification is given. The contribution of the resolution of MS instruments or their possibilities of a multiple fragmentation to the reliability of the identification is shown. This approach makes it possible to compare the reliability of identification with different MS instruments. Despite the small contribution of the separation of the chromatographic column compared to the MS separation, the role of the column in the identification is very important to distinguish isomers because their MS spectra are similar. 相似文献
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The characteristic features and the constituents of an identification procedure for chemical substances are discussed. This procedure is a screening of identification hypotheses followed by experimental testing of each one. The testing operation consists of comparison of the values of the quantities measured with other measurement results or reference data, resulting in the Student's ratio, the significance level, the matching of spectra, etc. The performance and the correctness of identification are expressed as "identification uncertainty", i.e. the probability of incorrect identification. The statistical significance level and other similarity values in spectra, chromatography retention parameters, etc. are the particular measures of uncertainty. Searching of prior data and estimation of the prior probability of the presence of particular compounds in the sample (matrix) to be analysed simplifies the setting up and cancelling of hypotheses during screening. Usually, identification is made by the analyst taking into account measurement results, prior information and personal considerations. The estimation of uncertainty and rules for the incorporation of prior data, make the result of identification less subjective. 相似文献
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Croci L Suffredini E Cozzi L Paniconi M Ciccaglioni G Colombo MM 《Journal of AOAC International》2007,90(6):1588-1597
Control of contamination by Vibrio parahaemolyticus in fishery products is often hampered by the lack of standardized methods and by the uncertainty associated with biochemical identification of the isolates. In this study, 5 polymerase chain reaction (PCR) methods for the identification of V. parahaemolyticus to the species level were evaluated by using 25 Vibrio reference strains and 163 isolates from fishery products, environmental sources, and clinical samples. Sequence targets of the methods were toxR, gyrB, and tlh genes (tested with 2 protocols), and the fragment pR72H. Isolate identification was confirmed by sequencing of the 16S rRNA gene and by PCR protocols for the identification of other Vibrio species. The PCR assay targeting the toxR gene achieved the highest performance (100% inclusivity and exclusivity). The 2 PCR protocols based on tlh gene detection, although showing the same inclusivity (100%), differed in the exclusivity (50 and 91%, respectively). Finally, the results provided by the PCR assays targeting the gyrB gene and pR72H fragment were less reliable and, in some cases, difficult to assess. According to the results of this study, the characteristics of accuracy expressed by the toxR identification method make it a suitable candidate as a reference method for the molecular identification of V. parahaemolyticus strains. 相似文献