Quantitative analysis of anthocyanins was performed on a series of blood orange juices according
to various spectrophotometric and HPLC methods, and the causes for different concentration
resulting from the application of such procedures were investigated. Spectrophotometric methods
utilizing aqueous ethanol as a solvent provided an anthocyanin content higher than that determined
by HPLC. Discrepancies were ascribed to the use of impure standards and/or unsuitable calibration
lines. The most consistent results with the HPLC findings were obtained by a method utilizing
water as a solvent and cyanidin-3-glucoside as a standard. Actual concentration of anthocyanins in
blood orange juice was remarkably lower than that currently determined by procedures used in the
juice producing factories.