Wang Chu-Fan, Li Liang
Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada.
Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada.
Anal Chim Acta. 2022 Sep 15;1226:340255. doi: 10.1016/j.aca.2022.340255. Epub 2022 Aug 14.
Chemical isotope labeling (CIL) LC-MS is a powerful tool for metabolome analysis with markedly improved metabolomic coverage and quantification accuracy over the conventional LC-MS technique. In addition, with differential isotope labeling, each labeled metabolite is detected as a peak pair in the mass spectra, offering the possibility of differentiating true metabolite peaks from the singlet noise or background peaks. In this study, we examined the effects of instrument type on the detectability of true metabolites with a focus on the comparison of quadrupole time-of-flight (QTOF) and Orbitrap mass spectrometers. Using the same ultra-high-performance liquid chromatography setup and optimized running conditions for QTOF and Orbitrap, we compared the total number of peak pairs detected and identified from the two instruments using human urine and serum as the test samples. Many common peak pairs were detected from the two instruments; however, there were a significant number of unique peak pairs detected in each type of instrument. By combining the datasets obtained using QTOF and Orbitrap, the total number of peak pairs detected could be significantly increased. We also examined the effect of mass resolving power on peak pair detection in Orbitrap (60,000 vs. 120,000 resolution). The observed differences in peak pair detectability were much less than those of QTOF vs. Orbitrap. However, the type of peak pairs detected using different resolutions could be somewhat different, offering the possibility of increasing the overall number of peak pairs by combining the two datasets obtained at two different resolutions. The results from this study clearly indicate that instrument type can have a profound effect on metabolite detection in CIL LC-MS. Therefore, comparison of metabolome data generated using different instruments needs to be carefully done. Moreover, future research (e.g., hardware modifications) is warranted to minimize the differences in order to generate more reproducible metabolome data from different types of instruments.
化学同位素标记（CIL）液相色谱-质谱联用技术是代谢组学分析的强大工具，与传统液相色谱-质谱技术相比，其代谢组覆盖范围和定量准确性显著提高。此外，通过差异同位素标记，每个标记的代谢物在质谱中被检测为一对峰，这使得从单峰噪声或背景峰中区分出真正的代谢物峰成为可能。在本研究中，我们重点比较了四极杆飞行时间（QTOF）质谱仪和轨道阱质谱仪，研究了仪器类型对真实代谢物可检测性的影响。使用相同的超高效液相色谱装置以及针对QTOF和轨道阱优化的运行条件，我们以人尿液和血清作为测试样品，比较了两种仪器检测和鉴定出的峰对总数。两种仪器检测到了许多共同的峰对；然而，每种仪器中都检测到了大量独特的峰对。通过合并使用QTOF和轨道阱获得的数据集，检测到的峰对总数可显著增加。我们还研究了质量分辨率对轨道阱中峰对检测的影响（分辨率分别为60,000和120,000）。观察到的峰对可检测性差异远小于QTOF与轨道阱之间的差异。然而，使用不同分辨率检测到的峰对类型可能会有所不同，这为合并在两种不同分辨率下获得的两个数据集以增加峰对总数提供了可能性。本研究结果清楚地表明，仪器类型对CIL液相色谱-质谱联用技术中的代谢物检测有深远影响。因此，需要谨慎比较使用不同仪器生成的代谢组数据。此外，有必要开展未来研究（如硬件改进）以尽量减少差异，从而从不同类型的仪器中生成更具可重复性的代谢组数据。
