The non-affinity absorption techniques provide the operator with methods that are benign, offer good resolution and excellent recovery of biologically active material. Mixed mode chromatography is the name given to chromatographic techniques that separate molecules based on more than one chromatographic principle. Hydrophobic interaction chromatography (HIC) and a variety of resins described as mixed modal provide the operator with additional techniques with excellent capacity, resolution and recovery but different selectivity. The binding and elution conditions should be determined empirically. This resin may provide a means to purify proteins that have proved troublesome to purify with conventional Ion exchange (IEX) or HIC. IEX chromatography is a versatile technique that can be used for the purification of biological molecules with charged functional groups, including proteins, peptides, amino acids, nucleotides, nucleic acids and charged metabolites. Chromatofocusing is a chromatographic technique that combines anion exchange chromatography with isoelectric focusing (IEF), separating proteins according to their isoelectric point.