To perform a quantitative analysis, approximately 3 mg samples of bark extracts were dried with internal standards. The mixtures were then dissolved in 500 μL of pyridine and 300 μL of a silylation reagent and kept in an oven for 1 h.
To analyse the extractive groups, 100 μg of four internal standards was used: heneicosanoic acid, betulin, cholesteryl margarate and 1,3-dipalmitoyl-2-oleoylglycerol. An Agilent 6850 GC-FID instrument equipped with a short HP-1/simulated distillation column (7.5 m × 0.53 mm, with a 0.15 μm film) was used for the analysis. The samples were injected on-column at 90 °C and detected using FID at 320 °C. The temperature program used was the same as in our previous study [10 (link)].
To perform an individual extractive analysis, 100 μg of heneicosanoic acid and the same amount of betulin were added as internal standards. An Agilent 6850 GC-FID instrument equipped with a long HP-5 column (30 m × 0.32 mm, with a 0.25 μm film) was used for the analysis. The samples were then injected at 290 °C and detected at 300 °C. The temperature program used was the same as in our previous study [10 (link)].
To analyse the esterified lipophilic extractives, the samples were hydrolysed and derivatised for analysis as described by Halmemies et al. (2021) [10 (link)].
To analyse the extractive groups, 100 μg of four internal standards was used: heneicosanoic acid, betulin, cholesteryl margarate and 1,3-dipalmitoyl-2-oleoylglycerol. An Agilent 6850 GC-FID instrument equipped with a short HP-1/simulated distillation column (7.5 m × 0.53 mm, with a 0.15 μm film) was used for the analysis. The samples were injected on-column at 90 °C and detected using FID at 320 °C. The temperature program used was the same as in our previous study [10 (link)].
To perform an individual extractive analysis, 100 μg of heneicosanoic acid and the same amount of betulin were added as internal standards. An Agilent 6850 GC-FID instrument equipped with a long HP-5 column (30 m × 0.32 mm, with a 0.25 μm film) was used for the analysis. The samples were then injected at 290 °C and detected at 300 °C. The temperature program used was the same as in our previous study [10 (link)].
To analyse the esterified lipophilic extractives, the samples were hydrolysed and derivatised for analysis as described by Halmemies et al. (2021) [10 (link)].