Juice samples were also extracted with ethyl acetate at pH 7.0 and pH 1.5 according to a modified method of Delage et al. [30]. HPLC analysis without further purification resulted in some peak impurities. Since the accurate quantification, especially of the flavonol glycosides, was impossible, solid-phase extraction had to be applied. As an alternative, the ethyl acetate extract was dried over sodium sulfate.The results obtained by both procedures were com-parable, however, drying with sodium sulfate proved to be a faster and cheaper method.