Assuring Quality and Consistency of Critical Reagents Using HRMS

The quality of Ligand Binding Assays (LBAs) is dependent on the use of quality Critical Reagents (CR). Typically, conjugations are performed by a procedure of buffer exchange, conjugation and a final buffer exchange using molecular weight cut-off or desalting spin columns. Incorporation is then determined by a wet chemistry method (e.g. HABA). Many of these procedures are not well controlled and do not ensure lot-to-lot consistency. By utilizing preparative SEC, High Resolution Mass Spectrometry (HRMS), analytical SEC (aSEC), and Tangential Flow Filtration (TFF), we have developed a method for ensuring uniformity of incorporation ratio, purity and concentration throughout the life cycle of a CR. This effectively eliminates the need for tedious and costly assay bridging and perhaps, revalidation.