Molecular mass analysis of antibodies by on-line SEC-MS.

Mass analysis of recombinant protein therapeutics is an important assay for product characterization. Intact mass analysis is used to provide confirmation of proper translation of the DNA sequence and to detect the presence of post-translational modifications such as amino acid processing and glycosylation. We present here a method for the rapid mass analysis of antibodies using a polyhydroxyethyl aspartamide column operated in size-exclusion mode and coupled with ESI-MS. This method allows extremely efficient desalting of proteins under acidic conditions that are optimal for subsequent mass analysis using standard ESI conditions. Furthermore, this technique is significantly faster and more sensitive than rpHPLC methods, typically considered the standard chromatography approach for mass analysis of proteins. This method is flexible and robust, and should prove useful for applications where a combination of speed and sensitivity are required.