Trace quantification of 1-octacosanol and 1-triacontanol and their main metabolites in plasma by liquid–liquid extraction coupled with gas chromatography–mass spectrometry

A method for the simultaneous determination of 1-octacosanol and 1-triacontanol and their main metabolites in rat plasma was developed. The procedure involved ethanolic NaOH saponification of the sample, acidification, liquid–liquid extraction, and derivatization of the analytes to its trimethylsilylether/ester, followed analysis by gas chromatography–mass spectrometry (GC–MS) in selected ion monitoring (SIM) mode. Quantification was performed by the internal standard method using betulin. The method had a good linearity over the range 8.4–540 ng/ml (r ≥ 0.998) and showed an excellent intra-day (R.S.D. = 0.59–3.06%) and inter-day (R.S.D. = 2.99–5.22%) precision according to the acceptance criteria. The detection limits ranged between 1.32 and 3.47 ng/ml. The method was applied successfully to study the total plasmatic concentration of 1-octacosanol, octacosanoic acid, 1-triacontanol, and triacontanoic acid, after an oral dose of policosanols mixture, using plasma samples of 100 μl.