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首页> 外文学位 >Surfactant-mediated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in the analysis of small biological molecules .
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Surfactant-mediated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry in the analysis of small biological molecules .

机译：表面活性剂介导的基质辅助激光解吸/电离飞行时间质谱分析小生物分子。

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摘要

As an analytical method, matrix-assisted laser desorption/ionization (MALDI) has been used primarily for the analysis of large biomolecules. However, its applications to small molecules have been limited. To try to circumvent this limitation, a variety of surfactants have been tested as matrix ion suppressors for the analysis of small molecules by matrix--assisted laser desorption lionization time-of flight mass spectrometry (MALDI-TOF-MS). Their addition to the common matrix alpha-cyano-4-hydroxycinnamic acid (CHCA) greatly reduces the presence of matrix-related ions when added at the appropriate mole ratio of CHCA/surfactant while still allowing the analyte signals to be observed. A range of cationic quaternary ammonium surfactants as well as a neutral and an anionic surfactant were tested for the analysis of phenolics, phenolic acids, peptides and caffeine. It was found that cationic surfactants, particularly cetyltrimethylammonium bromide (CTAB), were suitable for the analysis of acidic analytes. The anionic surfactant, sodium dodecylsulfate, showed promise for peptide analysis. The matrix:surfactant mole ratio was a critical parameter for suitable matrix ion suppression while allowing for an acceptable intensity of analyte signal. Of notable significance when using surfactants is that the resulting mass resolution of most analytes was improved by 25-75 %. No other study has observed this.;Surfactant-mediated MALDI-TOF-MS has been successfully used for the identification and quantitation of flavonoids from three berry extracts: lowbush blueberry (Vaccinium angustifolium), lingonberry (Vaccinium vitis-idaea), and blackberry (Rubus armeniacus). The use of the matrix CHCA led to extensive fragmentation of the sugar moiety of the glycosides, whereas 2,4,6-trihydroxyacetophenone (THAP) allowed for the intact glycoside molecule to be observed. The flavonoids were also analyzed by LC-UV-ESI-MS for comparison. The intact flavonoids could be quantified with RSD values of less than 10% and are comparable to LC. However, the use of MALDI greatly reduces the analysis time compared to traditional LC-MS methods.;In a second application, surfactant-mediated matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was successfully used in the analysis of caffeine and the vitamins riboflavin, nicotinamide and pyridoxine found in energy drinks. Of five common MALDI matrices tested, CHCA was found to be most suitable for the analysis of high sugar-containing energy drinks. Cetyltrimethylammonium bromide (CTAB) surfactant was suitable as a matrix-ion suppressor at a matrix:surfactant mole ratio of approximately 500: 1. For comparative purposes, LC-ESI-MS with UV detection was used. The calibration curves showed substantial improvement when the surfactant-mediated method was used compared to traditional MALDI, where correlation coefficients of 0.989 (nicotinamide), 0.991 (pyridoxine), 0.983 (caffeine) and 0.987 (riboflavin) were attained. Reproducibility experiments gave RSD values ranging from 9.7 to 18.1%and quantitative results were comparable to LC-MS.;Additional experiments were conducted to examine the homogeneity of the matrix:surfactant:analyte dried spots or order to explain the surfactant suppression phenomenon. Depth profiling of sample spots, by varying the number of laser shots, revealed that the surfactants tend to migrate toward the top of the droplet during dried droplet crystallization. It is likely that the analyte is also enriched in this surface region. This would lead to higher analyte/surfactant concentrations and reduced matrix-matrix interactions (known to be a major source of matrix-derived ions).
机译：作为一种分析方法，基质辅助激光解吸/电离（MALDI）主要用于分析大生物分子。但是，其在小分子上的应用受到限制。为了尝试克服此限制，已测试了多种表面活性剂作为基质离子抑制剂，用于通过基质辅助激光解吸电离飞行时间质谱（MALDI-TOF-MS）分析小分子。当它们以适当的CHCA /表面活性剂摩尔比添加时，它们添加到常见的基质α-氰基-4-羟基肉桂酸（CHCA）中可大大减少基质相关离子的存在，同时仍可观察到分析物信号。测试了一系列阳离子季铵盐表面活性剂以及中性和阴离子表面活性剂，以分析酚类，酚酸，肽和咖啡因。发现阳离子表面活性剂，特别是十六烷基三甲基溴化铵（CTAB），适用于酸性分析物的分析。阴离子表面活性剂十二烷基硫酸钠显示出可用于肽分析的前景。基质：表面活性剂的摩尔比是适当抑制基质离子同时允许可接受的分析物信号强度的关键参数。使用表面活性剂时，值得注意的是，大多数分析物的质量分辨率提高了25-75％。表面活性剂介导的MALDI-TOF-MS已成功用于三种浆果提取物中黄酮类化合物的鉴定和定量：低丛蓝莓（Vaccinium angustifolium），越橘（Vaccinium v​​itis-idaea）和黑莓（悬钩子基质CHCA的使用导致糖苷的糖部分广泛断裂，而2,4,6-三羟基苯乙酮（THAP）允许观察到完整的糖苷分子。还通过LC-UV-ESI-MS分析了类黄酮以进行比较。完整的类黄酮的定量RSD值可小于10％，与LC相当。但是，与传统的LC-MS方法相比，MALDI的使用大大缩短了分析时间。在第二种应用中，表面活性剂介导的基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF-MS）成功地用于分析咖啡因和能量饮料中发现的维生素核黄素，烟酰胺和吡ido醇。在五种常见的MALDI基质测试中，发现CHCA最适合分析高含糖能量饮料。十六烷基三甲基溴化铵（CTAB）表面活性剂适合作为基质离子抑制剂，基质与表面活性剂的摩尔比约为500：1。为了进行比较，使用具有UV检测功能的LC-ESI-MS。与传统的MALDI相比，当使用表面活性剂介导的方法时，校准曲线显示出显着改善，相关系数分别为0.989（烟酰胺），0.991（吡rid醇），0.983（咖啡因）和0.987（核黄素）。再现性实验的RSD值在9.7％至18.1％之间，定量结果与LC-MS相当。;另外进行了实验，以检查基质：表面活性剂：分析物干燥斑点的均匀性，或解释表面活性剂抑制现象。通过改变激光照射的次数，对样品斑点进行深度剖析，发现在干燥的液滴结晶过程中，表面活性剂趋于向液滴顶部迁移。分析物也可能在该表面区域富集。这将导致更高的分析物/表面活性剂浓度，并降低基质与基质的相互作用（已知是基质衍生离子的主要来源）。

著录项

  • 作者

    Grant, David Charles.;

  • 作者单位

    Memorial University of Newfoundland (Canada).;

  • 授予单位 Memorial University of Newfoundland (Canada).;
  • 学科 Chemistry Analytical.
  • 学位 Ph.D.
  • 年度 2010
  • 页码 163 p.
  • 总页数 163
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 普通生物学;
  • 关键词

  • 入库时间 2022-08-17 11:36:56

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