1 paper and diluted to 50 ml with distilled water. Then,
samples were passed through a 0.45 lm membrane filter.
An aliquot of 20 ll was injected into the HPLC system
using an NH2-Spherisorb S5 Column (250 · 4.6 mm,
5 lm). The eluent was acetonitrile:5 mM potassium dihydrogen
phosphate buffer adjusted to pH 3.5 (40:60). The
flow was isocratic at a rate of 1 ml/min at room temperature.
Detection was performed with a 486 Absorbance
Detector (Waters, Milford, MA, USA) at 254 nm. Results
were expressed as vitamin C retention related to the
untreated sample.