The scheme of the instrumental set
up was displayed inFig. 1. The diode-array detector (DAD) was
connected to a reaction coil (Peek, 15 m×0.25 mm) loaded into a
temperature controller. 10μL of sample wasfirstly separated on an
Agilent 1100 HPLC system equipped with a DAD. The separation of
phenolics was carried on an Agilent Zorbax SB C-18 column
(250 mm×4.6 mm i.d., 5μm) which was protected by a Zorbax SB
C-18 guard column (12.5 mm×4.6 mm i.d., 5μm). The HPLC condi-tion was expressed as follows: mobile phase was 0.1% (v/v) formic
acid (solvent A) and methanol (solvent B);flow rate was kept at
0.7 ml/min. The elution gradient was carried out as follows: solvent A
was 100%–40% from 0 to 45 min, 40%–0% in 5 min, and 0%–100% in
5 min. The temperature of the column was 35 °C. The DAD
wavelengths were set at 280 nm and 350 nm