Quantification of the phenolic compounds was carried out by
HPLC–ESI-QTOF-MS, using internal calibration with luteolin as
the internal standard (IS). The volume necessary to obtain a luteolin
final concentration of 1 mg/ml was added to the standards and
to the cranberry syrup samples. Extracted ion chromatograms of
each compound were used to obtain the areas used in the quantification
process.