Bromination
The bromination step was performed as described elsewhere
(Soares et al., 2006). Briefly, calcinated potassium bromide (1 g),
hydrobromic acid (150 lL) and saturated bromine solution
(2 mL) were added to the collected extract. The mixture was kept
on ice, in the dark, at least for 1 h. Sodium thiosulphate (150 lL)
was used to neutralise the excess of bromine. After adding NaCl
(4 g), a double liquid–liquid extraction with ethyl acetate/n-hexane
4:1 (v/v) (10 + 5 mL) was performed. The collected organic extract
was dried with anhydrous Na2SO4, centrifuged, concentrated
(N2, 60 C) to about 0.5 mL and injected in the gas chromatograph.