Samples (~2 g) were extracted by stirring with 25 mL of
meta-phosphoric acid (25 °C at 150 rpm) for 45 min and
subsequently filtered through Whatman No. 4 paper (Barros
et al. 2012). Before analysis by ultra fast liquid chromatograph
(UFLC) coupled to photodiode array detector (PDA),
the sample was filtered through 0.2 μm nylon filters. The
analysis was performed using a Shimadzu 20A series UFLC
(Shimadzu Coperation). Separation was achieved on a
SphereClone (Phenomenex) reverse phase C18 column
(5 μm, 250×4.6 mm i.d) thermostatted at 35 °C. The elution