AA was identified by comparing its retention time and ultravi- olet spectrum with that of the AA standard. UV-spectrum was also used to confirm the purity of AA separated from other possible compounds present in extract. Quantification of AA or vitamin C(as the sum of AA and DHAA) was done using the external standard method with AA as a standard. For each extract, at least two injec- tions were made. The content of DHAA was determined indirectly by subtraction of AA from TAA.