Protein adsorption–desorption on electrospray capillary walls – No influence on aggregate distribution

Adsorbed proteins on walls of glass capillaries used for electrospray (ES) can desorb and potentially affect size distributions and, thus, quantification of aggregates of proteins. In this study we use differential mobility analysis (DMA) to investigate the size distribution of various proteins eluting from bare and passivated glass capillaries. We found no significant differences in aggregate distributions from unpassivated capillaries at ‘steady state’ when compared to aggregate distributions from passivated capillaries implying that desorbing proteins do not influence protein aggregate distribution. Surface passivation with gelatin was found to be considerably more effective in limiting adsorption of two antibodies (Rituxan and polyclonal human IgG) compared to passivation with BSA. Gelatin passivation was also found to be stable for a few days and from a pH range of 4.8–9.0.

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► Developed a new methodology for passivating electrospray capillary surfaces.
► Proteins desorbing from electrospray capillary walls do not appear to influence aggregate distributions.
► Passivation of electrospray capillary surface with gelatin reduces adsorption of immunoglobulins.
► Used electrospray – differential mobility analysis for quantifying protein adsorption to electrospray capillary surface.