Determination of label efficiency and label degree of critical reagents by LC-MS and native MS.

Degree of labeling and label efficiency are key factors for optimal characterization of critical reagents that are used in ligand binding assays. Here, three case studies are shown demonstrating how liquid chromatography-mass spectrometry (LC-MS) was utilized to characterize critical reagents using three unique methodologies. Critical reagent batches were prepared for LC-MS analysis by use of: 20 mM dithiothreitol (DTT) (Case 1), rapid PNGaseF (Case 2), and a mobile phase diluent (Case 3).

Simple method to determine the concentration and incorporation ratio of ruthenium-labeled antibodies.

Ruthenium-labeled antibodies are commonly used detection reagents in bioanalysis assays and must be characterized to ensure quality. The aim of this work was to develop a method to determine the concentration and incorporation ratio (the degree of labeling [DOL]) of ruthenium-labeled antibodies by UV/VIS spectroscopy. Free SULFO-TAG compound was scanned using UV/VIS and showed an absorbance peak at 292 nm.