Determination of lignans in flaxseed using liquid chromatography with time-of-flight mass spectrometry

Preparation of flaxseed for lignan determination by gas chromatography-mass spectrometry method

“…The method of direct acid hydrolysis by Liggins et al (2000) was chosen since the literature data showed this method to result in the highest amounts of flaxseed SECO (12 617 µg/g and 7400 µg/g) detected. When applying ethanol or methanol extraction prior to acid, alkaline, or enzymatic hydrolyses, the detected amounts were in the range of 1570-6994 μg/g for SECO and 600-900 μg/g for ANHSECO (Milder et al 2004;Peñalvo et al 2005;Thompson et al 2006;Smeds et al 2007;Krajčová et al 2009;Popova et al 2009). Altough the discrepancy between the results of different methods could be explained by the differences in the plant variety and growth conditions ( Johnsson et al 2000), the work comparing alkaline hydrolysis of dioxane/ethanol extracts with direct alkaline hydrolysis showed better recovery of SDG using direct hydrolysis (Eliasson et al 2003).…”

“…Thus, four extractions showed to be sufficient for this type of flaxseed. In a previous work by Popova et al (2009), the ANHSECO SECO extraction efficiency was evaluated after 4 h, and additional 4 hours. After 8 h extraction with the solution of 80% (v/v) methanol in water at 55°C, the recovery of the analysed lignans was 80-97%.…”

“…The results of the four sample preparations applied were expressed as a sum of the concentrations of SECO and ANHSECO (μg/g of fresh edible seed) ( Table 2) because SECO is proven to dehydrate to ANHSECO under acid conditions (Mazur et al 1996;Meagher et al 1999;Charlet et al 2002), while only a negligible amount of ANHSECO is present in the free form in flaxseed (Popova et al 2009). The defatted and dried extracts were corrected to fresh weight based on the results of the oil (41.7 ± 0.9 g/100 g) and water (5.5 ± 0.2 g/100 g) contents determined.…”

“…Flaxseed was milled in a coffee grinder and either used for analysis or additionally defatted by Soxhlet extraction in n-hexane for 8 h (ISO 659:1998) and oven dried until constant mass. Defatting was also done by magnetic stir mixing of milled flaxseed in n-hexane (1:5 w/v) at room temperature for 1 h, and repeated once, referring to previous works that used stirring with n-hexane to remove the oil (Sicilia et al 2003;Popova et al 2009). The content of oil in flaxseed before and after stir mixing was determined by Soxhlet extraction (ISO 659:1998).…”

“…Up to now, acid or alkaline hydrolysis or combinations of these with enzyme hydrolysis have been applied to obtain lignan aglycones (Table 1). For the identification and quantification of lignans from food, high performance liquid chromatography (HPLC) with diode array detection (DAD) (Meagher et al 1999;Johnsson et al 2000;Eliasson et al 2003;Zhang & Xu 2007), coulometric electrode array (CEA) detection system (Kraushofer & Sontag 2002;Schwartz & Sontag 2006), and MS/MS detectors (Milder et al 2004;Smeds et al 2007) or GC/MS (Mazur et al 1996;Meagher et al 1999;Liggins et al 2000;Sicilia et al 2003;Peñalvo et al 2005;Thompson et al 2006;Popova et al 2009) have been used. In Table 1, the overview is given of the methods developed for flaxseed lignan gas chromatography-mass spectrometry (GC/MS) analysis.…”