Kuhlmann Christopher, Heide Maximilian, Engelhard Carsten
Department of Chemistry and Biology, University of Siegen, Adolf-Reichwein-Str. 2, 57076, Siegen, Germany.
Center for Micro- and Nanochemistry and Engineering, University of Siegen, Adolf-Reichwein-Str. 2, 57076, Siegen, Germany.
Anal Bioanal Chem. 2019 Sep;411(23):6213-6225. doi: 10.1007/s00216-019-02013-8. Epub 2019 Jul 17.
Thin-layer chromatography (TLC) was interfaced to high-resolution mass spectrometry (MS) using a flowing atmospheric-pressure afterglow (FAPA) ambient desorption/ionization source. The influence of different TLC stationary phases on the mass spectral signal response and mass spectral image quality in FAPA-MS was carefully investigated. Specifically, a mixture of selected analgesics (acetaminophen), alkaloids (nicotine and caffeine), and steroids (cortisone) was deposited on different stationary phases (silica plates, RP-modified silica plates, CN-modified silica plates, DIOL-modified silica plates, and NH-modified silica plates), and TLC plates with different thickness (100, 200, 250, 500, 1000, 2000 μm) of the stationary phase. After analyte separation, mass spectral imaging was performed of the complete TLC plate via FAPA-MS and the detected ion abundance was compared. It was found that TLC plates with larger particle sizes (10-12 μm) and thicker stationary phase layers (e.g., 1000 μm and 2000 μm) led to higher signals (protonated molecules) compared to smaller particles sizes (6-8 μm) and thinner stationary phases (e.g., 100 μm and 200 μm). Instrumental detection limits in the low ng-range/band were determined for TLC-FAPA-MS of caffeine from RP-modified TLC silica plates. Lastly, a quantitative TLC-FAPA-MS method using stable isotope dilution analysis was developed and applied to the quantification of caffeine in energy drinks. Graphical abstract.
使用流动大气压余辉（FAPA）常压解吸/电离源将薄层色谱（TLC）与高分辨率质谱（MS）联用。仔细研究了不同TLC固定相对FAPA-MS中质谱信号响应和质谱图像质量的影响。具体而言，将选定的镇痛药（对乙酰氨基酚）、生物碱（尼古丁和咖啡因）和类固醇（可的松）的混合物点样在不同的固定相（硅胶板、反相改性硅胶板、氰基改性硅胶板、二醇改性硅胶板和氨基改性硅胶板）以及具有不同固定相厚度（100、200、250、500、1000、2000μm）的TLC板上。分析物分离后，通过FAPA-MS对整个TLC板进行质谱成像，并比较检测到的离子丰度。结果发现，与较小粒径（6 - 8μm）和较薄固定相（例如100μm和200μm）相比，较大粒径（10 - 12μm）和较厚固定相层（例如1000μm和2000μm）的TLC板会产生更高的信号（质子化分子）。测定了反相改性TLC硅胶板上咖啡因的TLC-FAPA-MS在低ng/带范围内的仪器检测限。最后，开发了一种使用稳定同位素稀释分析的定量TLC-FAPA-MS方法，并将其应用于能量饮料中咖啡因的定量分析。图形摘要。
