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The molecular weight and molecular weight distribution greatly affect the properties of a polymer Classical polymer weight determination methods involve typically indirect methods, such as gel permeation chromatography(GPC), and light scattering .However, these methods are time-consuming and can not provide absolute molecular weight .MALDI/TOF has the ability to directly measure absolute molecular weight of polymer and molecular weight distribution. Besides average molecular weight, MALDI-TOF can provide information about the repeat unit and end group of the polymer. We analyzed several synthetic polymers by MALDI/TOF .Their average molecular weights were calculated and their molecular structures were proposed. 相似文献
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In positive-ion fast atom bombardment (FAB) mass spectrometry, it is difficult to determine the molecular weights of oligosaccharides due to the low abundance of [M H]^ ion. However, when oligosaccharides are mixed with an appropriate amount of NaCI and LiCI, two highly abundant peaks[M Na]^ and [M Li]^ appear in FABmass spectra and their mass difference is 16. From the adduct ions, the molecular weights of oligosaccharides can be determined unambiguously.In the same way, when a mixture of oligosaccharides was mixed with an appropriate amount of Na^ and Li^ , pairs of strong peaks appeared in the FAB mass spectra. These adduct ions were easily recognized due to the fact that they were very strong and their mass difference was union(16u). From these adduct ions, the molecular weight of each oligosaccharides in mixture may be determined. 相似文献
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溶剂的组成影响电喷雾离子(ESI)化效率。该研究观察了ESI溶剂体系中不同浓度的乙腈(ACN)对MRFA、Reserpine、ΜLtramark1621、马肌球蛋白酶切肽段等标准物质的质谱信号响应强度的影响,发现在溶剂体系中,ACN浓度达到70%时,上述物质的质谱信号强度具有最大值。根据这一现象, 对传统的反相色谱-电喷雾-质谱(RPLC-ESI-MS)系统进行管路改造,在分析柱后通过1个三通阀引入适当流速的有机溶剂进行辅助喷雾。对马心肌蛋白酶切肽段混合物的分析表明,该方法可以有效提高酶切肽段的检出率,并提高鉴定蛋白质的序列覆盖率。 相似文献
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聚醚多元醇是生产聚氨酯制品的主要原料,其相对分子质量及其分布对聚氨酯制品的性能有着直接影响.采用高分辨电喷雾质谱仪(ESI-MS)对聚醚多元醇进行分析,得到了其相对分子质量分布的质谱图,根据其中的同位素峰质荷比之差判断出分子离子峰的电荷态.各分子离子峰的强度代表了相应的相对分子质量聚醚多元醇的浓度,通过计算得到了准确的数均相对分子质量(Mn)、重均分子量(Mw)以及相对分子质量分布系数(PD).从各主要分子离子峰之间质荷比差值都是58,推断该聚醚多元醇以环氧丙烷为单体.该方法简便,快速,准确,分辨率及灵敏度高. 相似文献
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电喷雾质谱(ESI-MS)因具有灵敏度高、响应速度快、分辨率高、原位在线监测等特点,广泛应用于反应监测领域。本文主要从不同离子化技术角度,综述了电喷雾质谱在反应监测和机理研究方面的进展。重点介绍了在线电喷雾质谱技术,其中包括解吸附电喷雾离子化质谱(DESI-MS)、萃取电喷雾离子化质谱(EESI-MS)、纳升电喷雾离子化质谱(nESI-MS)、超声喷雾离子化质谱(SSI-MS)以及其他在线电喷雾离子化质谱在反应监测中的应用。最后,对电喷雾质谱在反应监测的发展趋势进行总结和展望。 相似文献
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质谱分子成像技术作为体内药物分析的新兴工具受到越来越多的关注,其中生物体内复杂基质的干扰是面临的关键问题之一。本研究利用高分辨质谱技术的优势,采用空气动力辅助离子化质谱成像方法(AFAI-MSI),建立了高特异性的整体动物体内药物成像分析新方法,以提高体内药物成像分析结果的准确性和可靠性。以候选新药右旋娃儿藤宁碱(S-(+)-deoxytylophorinidine, CAT)为研究对象,采用高分辨质谱全扫描与靶向扫描相结合的方式,对整体动物体内药物的分布进行AFAI-MSI分析。结果表明,该方法能够准确地反映药物特异性分布和处置情况。通过一次质谱成像实验,从整体动物水平同时实现了候选新药体内分布和药物干预下内源性代谢物的成像分析,为候选新药的早期研发提供思路与手段。 相似文献
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三元尼龙改性酚醛树脂的研究 总被引:6,自引:0,他引:6
研究了用三元尼龙以共混法和共聚法两种方式改性的酚醛树脂。结果表明,共聚改性远优于共混改性。共聚改性的酚醛树脂体系中,分散相三元尼龙颗粒细小均匀,分散相与连续相有良好的相容性,可大幅度提高其玻璃纤维增强塑料的力学性能,除能用于模压成型外,并能适用于注射成型,有着广阔的应用前景。 相似文献
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Soyasaponins were physiologically active components existed in high concentration in soy germs, Soyasaponins were isolated from soy germs with preparative HPLC method. Their structures were confirmed with characteristic reaction and ESI/MS as soyasaponin A1 S4 Ba Bb. and ESI/MS was found to be highly sensitive and accurate for the structural analysis of saponins. 相似文献
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