Fundamental Investigation of Signal Drift in Continuous Liquid Chromatography/High Resolution Mass Spectrometric Plasma Analysis Toward Global Metabolomics

Abstract

Global metabolomics (G-Met) is a method to simultaneously analyze many endogenous metabolites. It is a valuable tool for identifying disease biomarkers and disease-related pathways. However, obtaining reproducible and reliable G-Met results using liquid chromatography/high-resolution mass spectrometry (LC/HRMS) is challenging. This study aimed to investigate signal drift in continuous plasma LC/HRMS analysis. The LC/HRMS analytical system comprised a TripleTOF 5600 quadrupole timeof-flight hybrid tandem mass spectrometer and a Nexera ultra-high-performance LC system. The analytical column was a Poroshell 120 HILIC-Z PEEK (2.1 mm i.d. × 150 mm, 2.7 μm), with the column oven set at 40°C. Mobile phases A and B consisted of 10 mM ammonium bicarbonate in water/28% aqueous ammonia solution (100:0.1, v/v) and acetonitrile, respectively, and the flow rate was set at 0.3 mL/min. Eight compounds showed MS signal drift, even in the standard analysis. In positive ion mode plasma analysis, an increasing MS signal trend was observed for four compounds. In contrast, six metabolites exhibited a decreasing MS signal in negative ion mode. In particular, during the initial 20 LC/HRMS runs, seven metabolites showed MS signal drifts. In conclusion, stabilization by 20 initial injections and MS signal correction for drift are essential for reliable result of G-Met. We hope that the results of this study will inform future research on plasma G-Met studies.