Gas phase derivatization for lipidomic MS analysis

描述(由申请人提供)：目前获得认可的脂肪组学方法是基于对脂肪酰基及其在甘油脂的sn、2或3位的位置(区域特异性)的碳长和不饱和度的快速、全面的质谱仪(MS)分析。脂肪组学分析面临的最重要的分析问题是还没有出现一种通用的方法来同时提供脂肪酰基中的双键位置和区域特异性信息，我们建议开发一种新的质谱学方法，该方法应该能够完整、自动地表征粗脂提取物中所有酰化的脂类，离子-分子反应在化学电离(CI)质谱学(MS)中产生加合物，是有效的气相衍生化过程。在1999年以来的8篇系列论文中，我们报道了用乙腈CI/MS/MS对不饱和脂肪酸甲酯(FAME)进行气体衍生化的共同发现。产物的裂解为FAME的结构分析提供了第一个快速、方便的方法。乙腈CI产生m/z为54的离子，该离子跨双键共价加成；产生的[M+54]+离子在碰撞活化时经历电荷驱动的碎裂，以产生诊断离子，明确地确定多不饱和化合物中双键的位置。最近，在大气压下观察到了液体流动中的这种反应。我们提出了一种双管齐下的方法，其中1)建立基于乙腈的APCI，用于分析来自粗脂提取物的脂类中脂肪酰基的双键位置；2)完整地开发乙腈GClCIIMSLMS，包括分析所有多不饱和非亚甲基中断的脂肪酸。这些目标最终将结合在一起，与传统的MS/MS模式(前体、产物和中性损失扫描)一起，气相衍生酰基化合物的分析应该提供大多数甘油脂的完整结构和定量信息，并可以自动化进行脂体分析。

DESCRIPTION (provided by applicant): Lipidomic approaches now gaining acceptance are based on the rapid, comprehensive mass spectrometry (MS) analysis of carbon length and degree of unsaturation in fatty acyl groups and their positions (regiospecificity) at the sn 1,2, or 3 positions of glycerolipids. The most important analytical issue facing lipidomic analysis is that no general method has emerged that delivers double bond position in the fatty acyl groups simultaneously with regiospecific information, We propose to exploit a novel mass spectrometric method developed in our laboratory that should enable complete, automated characterization of all acylated lipids in crude lipid extracts, Ion-molecule reactions that result in adducts during chemical ionization (Cl) mass spectrometry (MS) are effectively a gas phase derivatization process. In a series of 8 papers since 1999, we reported co-discovery of gas derivatization of unsaturated fatty acid methyl esters (FAME) by acetonitrile CI/MS/MS. Fragmentation of the resulting adducts provides the first rapid, convenient structural analysis of FAME. Acetonitrile CI produces an ion at m/z 54 which adds covalently across double bonds; the resulting [M+54]+ ion undergoes charge-driven fragmentation upon collisional activation to yield diagnostic ions that unequivocally establish the position of double bonds in polyunsaturates. Recently, this reaction has been observed for atmospheric pressure CI in a liquid stream. We propose a two pronged approach where we 1) develop APCI based on acetonitrile for analysis of double bond position for fatty acyl groups within lipid classes derived from crude lipid extracts, and 2) complete development of acetonitrile GClCIIMSlMS to include analysis of all polyunsaturated non-methylene-interrupted fatty acids. These goals will eventually be coupled, and together with conventional MS/MS modes (precursor, product, and neutral loss scans), analysis of gas phase derivatized acyl-containing compounds should provide complete structural and quantitative information for most glycerolipids and can be automated for lipidomic analysis.