Use of Trifluoro-Acetate Derivatives for GC-MS and GC-MS/MS Quantification of Trace Amounts of Stera-3β,5α,6β-Triols (Tracers of Δ 5 -Sterol Autoxidation) in Environmental Samples

• Published in: Molecules (Basel, Switzerland) Switzerland), 2023-02, Vol.28 (4), p.1547
• Main Authors: Aubert, Claude, Rontani, Jean-François
• Format: Article
• Language: English
• Subjects: Acetates; Acetic acid; Analysis; Analytical chemistry; Autoxidation; autoxidation tracers; Chemical Sciences; Chemical tests and reagents; Cholesterol; Chromatography; derivatization; Desert environments; Environmental Sciences; Ethers; Fluorine; Gas chromatography; Gas Chromatography-Mass Spectrometry - methods; GC-EI(QTOF); Hydroxides; Hydroxyl groups; Instrument industry; Ions; Marine sediments; Mass spectra; Mass spectrometry; Mass spectroscopy; Monitoring; Oxidation; Particulate matter; Phytosterols; Reagents; Scientific imaging; Sediments; stera-3β,5α,6β-triols; Sterols; Sterols - chemistry; Stigmasterol; Tandem Mass Spectrometry; Tracers; Tracers (Chemistry); trifluoroacetylation; Triols; validation
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules28041547

Stera-3β,5α,6β-triols make useful tracers of the autoxidation of Δ -sterols. These compounds are generally analyzed using gas chromatography-mass spectrometry (GC-MS) after silylation. Unfortunately, the 5α hydroxyl groups of these compounds, which are not derivatized by conventional silylation reagents, substantially alter the chromatographic properties of these derivatives, thus ruling out firm quantification of trace amounts. In this work, we developed a derivatization method (trifluoroacetylation) that enables derivatization of the three hydroxyl groups of 3β,5α,6β-steratriols. The derivatives thus formed present several advantages over silyl ethers: (i) better stability, (ii) shorter retention times, (iii) better chromatographic properties and (iv) mass spectra featuring specific ions or transitions that enable very low limits of detection in selected ion monitoring (SIM) and multiple reaction monitoring (MRM) modes. This method, validated with cholesta-3β,5α,6β-triol, was applied to several environmental samples (desert dusts, marine sediments and particulate matter) and was able to quantify trace amounts of 3β,5α,6β-steratriols corresponding to several sterols: not only classical monounsaturated sterols (e.g., cholesterol, campesterol and sitosterol) but also, and for the first time, di-unsaturated sterols (e.g., stigmasterol, dehydrocholesterol and brassicasterol).