The separation and purification of antibodies is a fast growing and important area. Antibodies often have important and vital roles in the human immune system, such as immunoglobulin G (IgG). There exists four subclasses, denoted as IgG1, IgG2, IgG3 and IgG4, proportions of which are important in relation to human health and disease.  For each subclass there exists both a κ and a λ variant, whose proportions are also relevant. Separation and ultimate purification of IgG subclasses often involves protein A based affinity chromatography, however this is expensive, prone to ligand leakage from the sorbent and under elution conditions, the formation of aggregates is sometimes observed. Other techniques available also tend to be expensive and/or time consuming. The use of polymer-based monolithic columns is an attractive alternative, given their robustness, high permeability, fast mass transfer kinetics, as well as ease and affordability of synthesis.

In this work, we present the preparation of polymer monoliths in 150-μm i.d. capillaries by thermal polymerisation of poly(ethylene glycol) diacrylate for rapid hydrophobic interaction chromatography of IgG subclasses and related variants. The separations obtained will be presented, including baseline separation for mixtures of the κ variants of IgG1, IgG2 and IgG3 as well as the κ and λ variants of IgG1 and IgG2. The effect of eluent concentration and pH on the separation efficiency will also be demonstrated, resulting in almost baseline resolution to be achieved for mixtures of the κ variants of IgG1, IgG2, IgG3 and IgG4 but also the κ and λ variants of IgG1 and IgG2. These results were an improvement to those in previous reports, while maintaining a simple methodology. 

The incorporation of nanoparticles into this material and the associated difficulties will also be presented.