Ochoa Grant S, Billingsley Matthew C, Synovec Robert E
Department of Chemistry, University of Washington, Box 351700, Seattle, WA, 98195, USA.
Air Force Research Laboratory/RQRC, 10 E Saturn Boulevard, Edwards AFB, California City, CA, 93524, USA.
Anal Bioanal Chem. 2023 May;415(13):2411-2423. doi: 10.1007/s00216-022-04348-1. Epub 2022 Oct 1.
Tile-based Fisher ratio (F-ratio) analysis of comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC × GC-TOFMS) data is a powerful, supervised discovery methodology for pinpointing sample class-distinguishing analytes between two or more sample classes. Herein, we extend this analytical methodology to focus upon specific chemical groups in kerosene-based aerospace fuel using solid-phase extraction (SPE). Treating samples with SPE removes specific compounds depending on the SPE stationary phase (i.e., silica), creating an altered "pass" sample, identical to the original "neat" sample except for the extracted compounds. Application of F-ratio analysis to the neat samples against the pass samples provides global discovery with a numerically sorted hit list of all analytes affected by the SPE procedure. Sections of GC × GC-TOFMS data from the top analyte hits are reconstructed to form a "stitch" chromatogram to visualize the sample class-distinguishing compounds, revealing excellent agreement with the extract chromatogram. Additionally, utilizing the four-grid tiling scheme developed for tile-based F-ratio analysis, we demonstrate a tile-based pairwise analysis method, referred to as 1v1 analysis, to discover analytes that differ in concentration between two fuel chromatograms. Application of 1v1 analysis is highly efficient since replicates do not necessarily need to be run on the GC × GC-TOFMS instrument, which is beneficial for sample-limited applications. The 1v1 analyses discovered most of the same features as F-ratio analysis, ranging from 69 to 81% of the features discovered by F-ratio analysis while requiring one-sixth the data. Lastly, the overall methodology is applied to three candidate rocket fuels to better understand the compound class-distinguishing differences. The separate hit lists produced for high-concentration bulk hydrocarbon differences and low-concentration level polar compound differences provided valuable insight into these candidate rocket fuels.
基于瓦片的全二维气相色谱飞行时间质谱（GC × GC-TOFMS）数据的费舍尔比率（F比率）分析是一种强大的、有监督的发现方法，用于确定两个或多个样本类别之间区分样本类别的分析物。在此，我们扩展了这种分析方法，使用固相萃取（SPE）聚焦于基于煤油的航空燃料中的特定化学基团。用SPE处理样品会根据SPE固定相（即硅胶）去除特定化合物，从而产生一个经过改变的“通过”样品，除了被萃取的化合物外，它与原始的“纯”样品相同。将F比率分析应用于纯样品与通过样品，可实现全局发现，并生成一份按数值排序的受SPE程序影响的所有分析物命中列表。对顶级分析物命中的GC × GC-TOFMS数据部分进行重建，以形成“拼接”色谱图，以可视化区分样本类别的化合物，结果显示与萃取色谱图高度吻合。此外，利用为基于瓦片的F比率分析开发的四格平铺方案，我们展示了一种基于瓦片的成对分析方法，称为1v1分析，以发现两个燃料色谱图之间浓度不同的分析物。1v1分析的应用效率很高，因为不一定需要在GC × GC-TOFMS仪器上运行重复样品，这对于样本有限的应用是有益的。1v1分析发现的大多数特征与F比率分析相同，范围为F比率分析发现的特征的69%至81%，同时所需数据仅为六分之一。最后，将整个方法应用于三种候选火箭燃料，以更好地理解化合物类别区分差异。针对高浓度大量烃差异和低浓度水平极性化合物差异生成的单独命中列表，为这些候选火箭燃料提供了有价值的见解。
