QuikPrep® SpinColumns™ for cation exchange chromatography are filled with a negatively charged resin to attract positively charged molecules from samples. Matrices are available in either strong or weak ionised states. This expresses the ability of the exchange matrix to maintain its charge with a change in pH and not the strength of the bond. Strong exchangers have functional groups that will always remain ionised, while the functional groups of the weak exchangers can be neutralised by changing the pH.

Ion exchange chromatography (IEX) is an effective method of sample purification and fractionation based on molecular charge. Samples are passed through spin columns containing a predetermined matrix. Target molecules are captured and held by ionic bonds to the insoluble stationary matrix while the remaining sample is allowed to flow through the column. The ionic bonds are then broken through the addition of an elution buffer which changes the pH and alters the ionic strength of the molecules being retained. The bound molecules are eluted in order of the least to most strongly bound allowing for the collection of samples in fractions for separate analysis.