heroin quit ba chemistry basics here let's talk about ion exchange chromatography ion exchange chromatography is based on the phenomenon of attraction between opposite charges the stationary phase is selected such that it has a particular charge and attracts the sample molecules with the opposite charge the stationary phase is also known as the ion exchanger the ion exchange chromatography is widely used for the separation and purification of proteins peptides nucleic acids poly nucleotides etc the ion exchanger can be of two types cat ion exchanger and the anion exchanger guitar an exchanger has a negative charge and attracts positively charged cation while an exchanger is positively charged and attracts negatively charged anion different functional groups such as carboxyl carboxymethyl sulphur sulphur metal etc can be used as a cation exchange buffers having negatively charged ions like acetate phosphate etc can be used with cation exchanger on the other hand functional groups like amino I'll try methyl amino ethyle etc can be used as an ion exchanger the buffers used with an ion exchanger has a positive charge for example Tris buffer let's try to understand the separation of proteins with ion exchange chromatography and isoelectric pH the net charge and protein is zero that is proteins have equal number of positive and negative charge if the pH is shifted one unit above the isoelectric pH then the protein will have net negative charge [Music] and if a pH is shifted one unit below the isoelectric pH then the protein will have net positive charge before proceeding further it must be checked at which pH the protein is table of the protein is stable at pH one unit above isoelectric pH then an unexpected graph is preferred as the protein will have a negative charge and if the protein is stable one unit below the isoelectric pH then cation exchange chromatography is preferred as the protein will have a positive charge once the protein binds the stationary phase in the column illusion of protein can be done by changing in the pH or by changing the ironing strand [Music]