Simultaneous quantification of 18 saturated and unsaturated fatty acids and 7 sterols as their <i>tert</i>-butyldimethylsilyl derivatives in human saliva using gas chromatography-tandem mass spectrometry

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<P><B>Abstract</B></P> <P>The profiling of fatty acids (FAs) or sterols has been applied in clinical studies, but still needs to be improved to enable their simultaneous quantification. Moreover, little progress has been made in determining the levels of FAs and sterols in human saliva in a single run. In this study, gas chromatography-tandem mass spectrometry (GC–MS/MS) using one-step <I>tert</I>-butyldimethylsilyl (TBDMS) derivatization was developed for comprehensive profiling of 18 FAs (eight saturated, five monounsaturated, and five polyunsaturated FAs) and 7 sterols (cholesterol and its precursors). The TBDMS derivatization process was also optimized in terms of reaction solvent, catalyst, temperature, and reaction time. The optimized conditions resulted in better derivatization efficiency with good chromatographic separation through a high-temperature column within 23 min. The present method provided good linearity (<I>r</I> > 0.993), precision (coefficient of variation, 2.7% to 10.4%), and accuracy (91.5% to 103.4%). The overall recovery ranged from 73.8% to 114.3% for the 18 FAs, and from 68.9% to 79.8% for the 7 sterols. The validated method was applied to characterize FAs and sterols in human saliva samples. This is the first report of a GC–MS/MS method for the simultaneous determination of various FAs and sterols from a small volume (100 μL) of saliva. This approach can be used as a primary screening tool to examine the levels of both FAs and sterols in saliva, providing detailed information about their homeostasis for diagnostic and prognostic purposes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Both fatty acids and sterols were simultaneously measured from a small volume of human saliva. </LI> <LI> One-step <I>tert</I>-butyldimethylsilylation was developed for the simultaneous quantification of fatty acids and sterols. </LI> <LI> This GC-MS/MS method is a powerful analytical tool to measure salivary fatty acids and sterols in a single run. </LI> </UL> </P>