The 4-(dimethylamino)cinnamaldehyde assay quantifies soluble proanthocyanidins.
Cranberry proanthocyanidin (c-PAC) standard was compared to procyanidin A2 standard.
Use of A2 procyanidin standard results in underestimation of proanthocyanidins.
No significant effect (P > 0.05) of operator or day on estimation of proanthocyanidin.
Adoption of c-PAC standard improves accuracy of proanthocyanidin quantification.