The content of total anthocyanins can be determined by the pH difference method

pH (GIUSTI; WROSLTAD, 2001), in which it is dissolved in two buffer systems:

potassium chloride - hydrochloric acid pH 1.0 (0.025M) and sodium acetate pH

4,5 (0,4M). The sample after extraction is diluted in the buffer solutions to a dilution factor equal to 100 (to obtain an optical density in the range 0.100-1.200

at 514 nm) and measurements were performed on absorption maxima in the visible region and at 700 nm. The concentration of monomeric pigments in the extract is calculated and represented as cyanidin-3-glycoside.

Dear sir

The total anthocyanin content (TAC) was determined by the pH-differential method.[12] 1 ml of TAE solution (1 mg/ml) was mixed separately with 9 ml buffer at pH 1.0 (0.1 M HCl/4.9 mM KCl) and another at pH 4.5 (24.8 mM sodium acetate), and then the mixtures were balanced for 1 h in the dark. Absorbance was measured in a WFZ UV-2000 UV and visible spectrophotometer at 510 nm and 700 nm in buffers of pH 1.0 and pH 4.5, respectively. TAC was expressed as milligrams cyanidin-3-glucoside equivalents per gram of dry weight purification (mg C-3-G/g DW) and calculated via the following formula:

you can read

Total anthocyanins and cyanidin-3-O-glucoside contents and antioxidant activities of purified extracts from eight different pigmented plants

DOI: 10.4103/pm.pm_162_18

Thanks for your answer but the DOI is not downloading the paper via sci-hub. please can you kindly share the tittle of the paper @Nahla tariq

For determination of the total anthocyanins content by the spectrophotometric pH differential method. 0.4 mL of extraction mixed with 3.6 mL potassium chloride solution (KCl, 0.025 M, pH 1.0) and sodium acetate solution (0.4 M, pH 4.5). The pH values of KCl and sodium acetate solutions should be adjusted with 0.5 M aqueous formic acid solution. The absorbance of each dilution should be measured at 530 or 700 nm against a distilled water blank by using a spectrophotometer. The total anthocyanins content should be calculated according to Tang et al. 2017, https://doi.org/10.1016/j.jff.2017.01.015.

Thank you for your answer was really helpful @fawze, Nahla and carolina