Quantitative analysis of phenolic compounds was performed by
HPLC using an Agilent 1200 HPLC system (Waldbronn, Germany)
equipped with an Agilent 1200 series VWD detector, autosampler,
and a Zorbox SB-C18 column (250 4.6 mm i.d., 5 lm; Agilent
Technologies, Palo Alto, CA, USA); column temperature was maintained at 30 C.