SSCI offers a full complement of chromatographic as well as electrophoretic separation techniques as listed below:
- Electrophoresis
- SDS-PAGE
- Native PAGE
- Isoelectric Focusing
- Chromatography
- Reversed-phase HPLC
- Ion Exchange HPLC
- Size Exclusion HPLC
- Affinity
Related substances, as the name suggests, are components of a protein product that are derived from the parent protein molecule. Related substances can be divided into 2 types, product-related substances and product-related impurities. These definitions are taken from ICH Q6B. "Product-related substances are molecular variants of the desired product formed during manufacture and/or storage which are active and have no deleterious effect on the safety and efficacy of the drug product. These variants possess properties comparable to the desired product and are not considered impurities." On the other hand, "Product-related impurities are molecular variants of the desired product (eg, precursors, certain degradation products arising during manufacture and/or storage) which do not have properties comparable to those of the desired product with respect to activity, efficacy and safety."
Related substances may include such variants as oxidized forms, proteolyzed forms, aggregates, deamidated forms, and disulfide variants as well as many others. The general approach to the characterization of these substances is to isolate a sufficient quantity, often from a side stream from an early up scaled development run, and then to apply the techniques of protein characterization that are commonly used. It is often necessary to measure the biological activity of the related substance to categorize it as an impurity or not.