The
resultant mixtures were cited as ‘‘AQ3’’ and ‘‘AQ4’’. Finally, 2 mL
of ‘‘EA1’’, 4 mL of ‘‘EA2’’, ‘‘AQ3’’ and ‘‘AQ4’’ solution were diluted
to 25 mL with 95% ethanol, respectively, and their absorbance at
380 nm was recorded as EA, EC, ED and EB, respectively