Dear Sir. Concerning your issue about determination of anthocyanins dosage without calibration curve . The anthocyanins of red tart cherries (Prunus cerasus L. var. Montmorency), at different maturity levels, were extracted with 1% methanolic HCI and the total anthocyanin content of each stage calculated with the aid of a molar‐extinction coefficient at 530 mμ. The pigment solution for each stage of maturity was purified by adsorption on AG 50W × 4 cation-exchange resin, concentrated and separated by descending chromatography. The relative intensities of the 7 well‐defined pigments were measured photodensitometrically. The individual pigment content was calculated from the total anthocyanin content and the ratio of individual anthocyanin for each stage of maturity. The stage of maturity of the red tart cherry is an important factor influencing the total and individual anthocyanin content in cherries. This work also helps to give a greater insight into the development of anthocyanins in the maturing red tart cherry. I think the following below links may help you in your analysis:

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2621.1970.tb12147.x https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5613902/pdf/zfnr-61-1361779.pdf

Thanks