Figure 6. The raw ESI spectrum of the mPEG 1K-labeled mouse IgG1 mAb (top) and the ProMass HR deconvoluted spectrum (bottom). The broader deconvoluted peaks contain an abundance of masses which correspond to the average conjugation range shown in the spectrum (bottom), this is due to the polydispersive character of the mPEG 1K molecules. Low level polydispersed peaks lead to the production of deconvolution artifacts shown in clusters to the right of the “5-7 label peak”; based on the molar ratio for conjugation it is unlikely that these peaks represent real conjugates.
