Evaluation of product equivalence during process optimization for manufacture of a human IgM monoclonal antibody.

We have developed a battery of tests to characterize monoclonal antibodies and assess the effect of potential manufacturing process changes. Tryptic peptide mapping, molecular weight determination by HPLC and classical light scattering, isoelectric focussing, oligosaccharide mapping by HPAE-PAD chromatography, circular dichroism spectra and differential scanning calorimetry were applied as sensitive assays of antibody structure. Biological activity was assessed by measurement of specific antigen binding activity, binding spectrum and opsonic activity.

Analysis of alkyl sulfates in protein solutions by isocratic and gradient ion chromatography.

An ion-chromatographic analysis for separation and quantitation of long-chain alkyl sulfates in both commercial samples of sodium dodecyl sulfate (SDS) (lauryl sodium sulfate) and protein solutions was developed. The separation was performed on a hydrophobic resin-based column utilizing tetrabutylammonium hydroxide as an ion-pair reagent and acetonitrile as an organic modifier. Sensitive and selective detection of alkyl sulfates was achieved with an anion suppressor and a conductivity detector.