Development and validation of an ultra-high performance liquid chromatography-high resolution mass spectrometry method for simultaneous quantification of cyanogenic glycosides and secoisolariciresinol diglucoside in flaxseed (Linum usitatissimum L.).

An ultra performance liquid chromatography electrospray ionization high-resolution mass spectrometry (UPLC/ESI-HRMS) method was developed and validated for simultaneous quantification of cyanogenic glycosides (CGs), [linustatin (LIS) and neolinustatin (NLIS)], and the main lignan, secoisolariciresinol diglucoside (SDG) in Linoforce® (LF) [flaxseed (Linum usitatissimum L.) coated with two herbal extracts (Senna alexandrina mill and Frangula alnus)]. CGs and SDG were extracted from defatted ground LF by a new procedure consisting of an aqueous methanol ultrasound-assisted extraction followed by an aqueous alkaline ultrasound-assisted extraction of the residue. The combined extracted solutions were then hydrolyzed by 0.02 M NaOH to release SDG from its hydroxymethyl glutaryl ester-linked complex (SDG-HMG). After hydrolysis, the sample was acidified and analyzed directly, without the need of any additional clean-up steps, by UPLC/ESI-HRMS in positive mode. The identification of CGs and SDG was confirmed by the similar retention time and similar MS spectra to the corresponding authentic standards. The quantification was performed using the corresponding extracted ion chromatograms and amygdalin as internal standard. The overall method was validated in terms of linearity, stability, selectivity, precision and accuracy. The developed method was successfully applied to the quantification of CGs and SDG in LF and also in non-coated flaxseed. This is the first report on the simultaneous quantification of CGs and SDG in LF and flaxseed.