Bridging Targeted (Zeno MRM-HR) and Untargeted (SWATH) LC-HRMS in a Single Run for Sensitive Exposomics.

Area of Science:

• Analytical Chemistry
• Environmental Science
• Biochemistry

Background:

• Traditional chemical exposure assessment relies on low-resolution mass spectrometry with targeted approaches, limiting comprehensive analysis.
• Untargeted metabolomics offers broad compound coverage but struggles with sensitivity for ultratrace biomonitoring.
• A gap exists between high sensitivity and broad chemical coverage in small-molecule omics.

Purpose of the Study:

• To develop and validate a combined targeted/untargeted LC-MS method for enhanced exposomic analysis.
• To merge Multiple Reaction Monitoring-High Resolution (MRM-HR) and SWATH experiments using Zeno technology in a single analytical run.
• To improve sensitivity and detection frequency for ultratrace chemical biomonitoring.

Main Methods:

• Development of a hybrid LC-MS method combining MRM-HR and SWATH experiments.
• Optimization of Multiple Reaction Monitoring (MRM) transitions for 135 diverse chemicals, including toxicants and xenobiotics.
• Analysis of human plasma (SRM 1950) and serum (SRM 1958) standard reference materials using Zeno MRM-HR + SWATH and SWATH-only methodologies.

Main Results:

• The Zeno MRM-HR + SWATH method demonstrated a significant increase in sensitivity, detecting 2.2 and 3 times lower concentrations in SRMs 1950 and 1958, respectively.
• Detection frequency increased by 68% (from 19 to 32 positive detections) in the hybrid mode compared to SWATH-only.
• Successful optimization of MRM transitions for a diverse panel of 135 compounds.

Conclusions:

• The developed combined targeted/untargeted LC-MS method effectively balances high sensitivity with broad chemical coverage for exposomic applications.
• This approach offers a promising solution for ultratrace biomonitoring challenges in small-molecule omics.
• The methodology has potential for transferability to lipidomics and metabolomics workflows.