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Sarajlija H., Čukelj N., Novotni D., Mršić G., Brnčić M., Ćurić D. (2012): Preparation of flaxseed for lignan determination by gas chromatography-mass spectrometry method. Czech J. Food Sci., 30: 45-52.Since 1980s, several methods for the determination of lignans in food samples have been developed depending on the types of lignans and foods analysed, but mostly on flaxseed as a reference food. In this work, specific steps in flaxseed preparation for lignan secoisolariciresinol analysis by gas chromatography-mass spectrometry method were examined. Ethanol extraction of lignan from defatted and non-defatted flaxseed before acid hydrolysis yielded significantly lower concentrations (5172 ± 49 μg/g; 5159 ± 83 μg/g, respectively), when compared to the direct acid hydrolysis (8566 ± 169 μg/g; 8571 ± 192 μg/g, respectively). In the analysed samples of defatted and dried flaxseed, no significant difference in lignan content was observed when compared to non-defatted flaxseed samples.

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The aim of this study was to investigate leachable components (monomers) in high and low viscosity dental bulk-fill resin composites and conventional resin composite materials after polymerization. Six bulk-fill and six conventional dental resin composite materials were used in this study. The samples of each material (three sets of triplicates) were cured for 20 s with irradiance of 1200 mW/cm2 with a LED curing unit and immersed in a 75% ethanol solution at 37 °C. The eluates from each triplicate set were analyzed after 24 h, 7 days or 28 days using liquid chromatography coupled with triple quadrupole tandem mass spectrometry (LC-MS/MS). Detectable amounts of 2-Hydroxyethyl methacrylate (HEMA) were found in both Gradia materials and the amount observed across different time points was statistically different (p ˂ 0.05), with the amount in solution increasing for Gradia and decreasing for Gradia Direct flo. Bisphenol A diglycidildimethacrylate (BIS GMA) was found in Filtek and Tetric materials. Triethylene glycol dimethacrylate (TEGDMA) was detected in all materials. On the other hand, there were no statistically significant differences in the amounts of TEGDMA detected across different time points in either of the tested materials. Monomers HEMA, TEGDMA, 4-dimethylaminobenzoic acid ethyl ester (DMA BEE) and BIS GMA in bulk-fill and conventional composites (high and low viscosity) can be eluted after polymerization. The good selection of composite material and proper handling, the following of the manufacturer’s instructions for polymerization and the use of finishing and polishing procedures may reduce the elution of the unpolymerized monomers responsible for the possible allergic and genotoxic potential of dental resin composites.