Antibody drug conjugates (ADCs) are potent and specific biopharmaceuticals. These large molecules are typically analyzed using ELISA methods, which do not have the selectivity to accurately quantify the ADC alone. HPLC-MS/MS analysis of the digested antibody is an alternative approach that provides better selectivity. In order to increase the sensitivity of the method the analysis was conducted using microflow HPLC (MFLC). Additionally, the internal standard was aliquotted prior to denaturing the ADC in order to compensate for any preparation variability.

The extraction of large molecules using immunocapture techniques to remove endogenous plasma proteins or capture the target protein can be very expensive and time consuming. The pellet digestion method developed allows for cost effective, accurate, precise and selective quantitative analysis of the ADC SigmaMAb Mimic from plasma via MFLC-MS/MS in only a few hours.