Pedersen Christian Schack, Lauritsen Frants Roager, Sysoev Alexey, Viitanen Anna-Kaisa, Mäkelä Jyrki M, Adamov Alexey, Laakia Jaakko, Mauriala Timo, Kotiaho Tapio
Department of Chemistry, University of Copenhagen, Copenhagen, Denmark.
J Am Soc Mass Spectrom. 2008 Sep;19(9):1361-6. doi: 10.1016/j.jasms.2008.05.024. Epub 2008 Jun 17.
Ionized acetates were used as model compounds to describe gas-phase behavior of oxygen containing compounds with respect to their formation of dimers in ion mobility spectrometry (IMS). The ions were created using corona discharge at atmospheric pressure and separated in a drift tube before analysis of the ions by mass spectrometry. At the ambient operational temperature and pressure used in our instrument, all acetates studied formed dimers. Using a homolog series of n-alkyl-acetates, we found that the collision cross section of a dimer was smaller than that of a monomer with the same reduced mass. Our experiments also showed that the reduced mobility of acetate dimers with different functional groups increased in the order n-alkyl <or= branched chain alkyl <or= cyclo alkyl < aromat. For mixed n-alkyl dimers we found that the reduced mobility of acetate dimers having the same number of carbons, for example a dimer of acetyl acetate and hexyl acetate has the same reduced mobility as a dimer composed of two butyl acetates. The fundamental behavior of acetate monomers and dimers described in this paper will assist in a better understanding of the influence of dimer formation in ion mobility spectrometry.
离子化乙酸盐被用作模型化合物，以描述含氧化合物在离子迁移谱（IMS）中形成二聚体时的气相行为。离子通过大气压下的电晕放电产生，并在漂移管中分离，然后通过质谱分析离子。在我们仪器使用的环境操作温度和压力下，所研究的所有乙酸盐都形成了二聚体。使用一系列正烷基乙酸酯同系物，我们发现二聚体的碰撞截面小于具有相同折合质量的单体的碰撞截面。我们的实验还表明，具有不同官能团的乙酸盐二聚体的折合迁移率按正烷基≤支链烷基≤环烷基≤芳基的顺序增加。对于混合正烷基二聚体，我们发现具有相同碳原子数的乙酸盐二聚体的折合迁移率相同，例如乙酰乙酸酯和己基乙酸酯的二聚体与由两个丁基乙酸酯组成的二聚体具有相同的折合迁移率。本文描述的乙酸盐单体和二聚体的基本行为将有助于更好地理解离子迁移谱中二聚体形成的影响。
