Chemical Exposomics in Human Plasma by Lipid Removal and Large-Volume Injection Gas Chromatography-High-Resolution...

Area of Science:

• Analytical Chemistry
• Environmental Health Sciences
• Biochemistry

Background:

• Comprehensive chemical exposomics in blood requires advanced analytical workflows.
• Minimizing lipid coextractives is crucial for enhancing gas chromatography-high-resolution mass spectrometry (GC-HRMS) sensitivity.
• Current methods face challenges with matrix interference and limited injection volumes.

Purpose of the Study:

• To develop an improved GC-HRMS workflow by minimizing lipid coextractives for enhanced sensitivity and molecular discovery.
• To enable larger injection volumes and reduce matrix interference in plasma analysis.
• To establish a robust method for quantitative and non-targeted chemical exposomics.

Main Methods:

• Developed a simple isohexane (H) and acetonitrile-plasma (A-P) extraction protocol (HA-P) for small plasma volumes (100-200 μL).
• Utilized gas chromatography-Orbitrap high-resolution mass spectrometry (GC-Orbitrap HRMS) with large-volume injections (LVIs; 25 μL).
• Validated the method for quantitative analysis of hydrophobic analytes (log Kow > 3.0) and performed non-targeted analysis.

Main Results:

• The HA-P method effectively removed major lipids, enabling robust LVIs in long GC-HRMS sequences.
• Achieved a median method quantification limit of 0.09 ng/mL with good accuracy for certified reference serum.
• Detected 51 of 103 target analytes in a Swedish cohort (n=32) and identified 112 structures in non-targeted analysis.

Conclusions:

• The HA-P method significantly enhances GC-HRMS for chemical exposomics by reducing lipid interference.
• The protocol is quantitative, sensitive, and scalable for cohort studies, improving both targeted and non-targeted analyses.
• This workflow is compatible with existing liquid chromatography-based exposomics approaches.