Identification and Quantification of Aerosol Polar Oxygenated Compounds Bearing Carboxylic or Hydroxyl Groups. 1. Method Development
作者：M. Jaoui、T. E. Kleindienst、M. Lewandowski、E. O. Edney
DOI：10.1021/ac049919h
日期：2004.8.1
In this study, a new analytical technique was developed for the identification and quantification of multifunctional compounds containing simultaneously at least one hydroxyl or one carboxylic group, or both. This technique is based on derivatizing first the carboxylic group(s) of the multifunctional compound using an alcohol (e.g., methanol, 1-butanol) in the presence of a relatively strong Lewis acid (BF3) as a catalyst. This esterification reaction quickly and quantitatively converts carboxylic acids to their ester forms. The second step is based on silylation of the ester compounds using bis(trimethylsilyl) trifluoroacetamide (BSTFA) as the derivatizing agent. For compounds bearing ketone groups in addition to carboxylic and hydroxyl groups, a third step was used based on PFBHA derivatization of the carbonyls. Different parameters including temperature, reaction time, and effect due to artifacts were optimized. A GC/MS in EI and in methane-CI mode was used for the analysis of these compounds. The new approach was tested on a number of multifunctional compounds. The interpretation of their EI (70 eV) and CI mass spectra shows that critical information is gained leading to unambiguous identification of unknown compounds. For example, when derivatized only with BF3−methanol, their mass spectra comprise primary ions at m/z M•+ + 1, M•+ + 29, and M•+ − 31 for compounds bearing only carboxylic groups and M•+ + 1, M•+ + 29, M•+ − 31, and M+. − 17 for those bearing hydroxyl and carboxylic groups. However, when a second derivatization (BSTFA) was used, compounds bearing hydroxyl and carboxylic groups simultaneously show, in addition to the ions observed before, ions at m/z M•+ + 73, M•+ − 15, M•+ − 59, M•+ − 75, M•+ − 89, and 73. To the best of our knowledge, this technique describes systematically for the first time a method for identifying multifunctional oxygenated compounds containing simultaneously one or more hydroxyl and carboxylic acid groups.
在本研究中，开发了一种新的分析技术，用于鉴定和定量含有至少一个羟基或一个羧基或两者的多官能团化合物。该技术基于首先使用醇（例如甲醇、1-丁醇）在相对较强的路易斯酸（BF3）催化下对多官能团化合物的羧基进行衍生化。这种酯化反应迅速且定量地将羧酸转化为酯形式。第二步是使用双(三甲基硅基)三氟乙酰胺（BSTFA）作为衍生化剂对酯化合物进行硅烷化。对于除羧基和羟基外还含有酮基的化合物，采用了基于PFBHA对羰基进行衍生化的第三步。优化了包括温度、反应时间和因人工产物引起的影响等多个参数。使用电子轰击源（EI）和甲烷化学电离（CI）模式的气相色谱/质谱法（GC/MS）分析了这些化合物。对多种多官能团化合物测试了新方法。对其EI（70 eV）和CI质谱的解释表明，获得了关键信息，从而能够明确鉴定未知化合物。例如，仅通过BF3−甲醇衍生化时，它们的质谱包含仅含有羧基的化合物的离子m/z M•+ + 1、M•+ + 29和M•+ − 31，以及同时含有羟基和羧基的化合物的离子m/z M•+ + 1、M•+ + 29、M•+ − 31和M•+ − 17。然而，当使用第二步衍生化（BSTFA）时，同时含有羟基和羧基的化合物除了之前观察到的离子外，还显示出m/z M•+ + 73、M•+ − 15、M•+ − 59、M•+ − 75、M•+ − 89和73的离子。据我们所知，这项技术首次系统地描述了一种鉴定同时含有一个或多个羟基和羧酸基团的多官能团含氧化合物的方法。
