Drug-to-Antibody Ratio (DAR) by UV/Vis Spectroscopy

UV/Vis spectroscopy is a simple and convenient method to determine protein concentrations as well as the average number of drugs that are conjugated to the antibody in an antibody-drug conjugate (ADC). Using the measured absorbances of the ADC and the extinction coefficients of the antibody and the drug, the average drug-to-antibody ratio (DAR) can be determined.