QUALIFICATION OF GRAPE JUICE DRINKS AND DETERMINATION OF ITS OLIGOMERIC PROANTHOCYANIDINS (OPC) CONTENT BY HPLC

Qualification of grape juice drinks was performed by comparing the characteristic chromatographic peaks in the chromatogram of the sample with those of the standard or reference sample.Based on the presence or not of those specific chromatographic peaks,judgement of the quality of sample was drawn.In the HPLC determination of contents of OPC,reverse-phase separation was carried out on a C18 (ODS) chromatographic column (250 mm×4.6 mm,5 μm).A mixture containing methyl cyanide,water and trifluoroacetic acid in the proportion of 13 to 87 to 0.05 by volume was used as the mobile phase.UV-detector was used in both qualitative and quantitative analysis.Precision and recovery of this method were tested giving results of RSD′s in the range of 1.3%-1.7% and of recoveries in the range of 91%-116%.Validity of the proposed method was checked by a comparative analysis with the conventional colorimetric method,giving results of higher reliability.