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Published on: April 17, 2018
Position-Specific Hydrogen Isotope Analysis of Palmitic Acid by GC-Orbitrap Mass Spectrometry.
Kesi Yang1,2, Longchen Zhu1,2, Yihang Hong1,2
1International Center for Isotope Effects Research (ICIER), State Key Laboratory of Critical Earth Material Cycling and Mineral Deposits, Nanjing University, Nanjing 210023, China.
Analytical Chemistry
|June 23, 2026
Summary
This study introduces a new method for position-specific hydrogen isotope analysis (PSIA) of fatty acids using GC-Orbitrap. This technique offers enhanced sensitivity for metabolic studies and cancer diagnosis with nanomolar sample quantities.
Area of Science:
- Biogeochemistry
- Analytical Chemistry
- Metabolomics
Background:
- Hydrogen isotope composition (δ²H) of fatty acids is a valuable proxy for cellular metabolism and cancer diagnosis.
- Conventional gas chromatography-isotope ratio mass spectrometry (GC-IRMS) methods provide only molecular-average isotopic values, limiting insights into metabolic processes.
- Position-specific variations in hydrogen isotopes offer greater sensitivity to metabolic pathways.
Purpose of the Study:
- To develop and validate a method for position-specific hydrogen isotope analysis (PSIA) of fatty acids.
- To enable precise δ²H measurements on nanomolar sample quantities.
- To enhance the application of fatty acid isotope analysis in geological, environmental, and medical research.
Main Methods:
- Utilized a GC-Orbitrap (Exploris 240 GC) for isotopologue ratio acquisition of specific fragment ions in palmitic acid methyl esters.
- Implemented a custom peak-broadening system with switch-valves and a sample loop for extended acquisition times (12 min).
- Analyzed samples with a low consumption of 7.6 nmol, achieving experimental precision of 5.4‰ for C₄H₇O₂⁺ and 8.8‰ for C₅H₉O₂⁺.
Main Results:
- Demonstrated negligible hydrogen scrambling using a 12th position labeled palmitic acid standard.
- Achieved a near-precise match with GC-IRMS whole-molecule δ²H measurements (correlation slope of 1.044) across a wide composition range (-223–418‰).
- Established a robust method for position-specific δ²H measurement of fatty acids at the nanomolar scale.
Conclusions:
- The developed GC-Orbitrap method enables accurate position-specific hydrogen isotope analysis of fatty acids.
- This advancement allows for more sensitive tracing of cellular metabolic pathways and rates.
- The method holds significant potential for novel applications in geology, environmental science, and medical diagnostics, including cancer research.
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