Conductivity and pH Monitoring Optimizes Protein Separations

Ion exchange column chromatography has been a key method for the separation and purification of proteins for over thirty years. The need for faster separation of large, labile biomolecules has led to the development of ion exchange HPLC columns and techniques. The separation must not only be rapid, but must give high recovery of the component of interest and must not appreciably affect the biological activity of the recovered component. Proteins which are now being separated and purified by ion exchange include monoclonal antibodies and interferons, viral proteins, and various intracellular proteins. Both the classical column and the new HPLC methods require a simple, yet reliable and reproducible, technique for tracking the protein of interest as it elutes from the column. Experience has taught that this tracking can be accomplished by monitoring eluent conductivity during the separations, since a protein will usually elute from the column at the same conductivity value run after run. Flow through conductivity monitors required to fill this need have in the past either been very expensive or have lacked the desired dead volume or conductivity range. Lazar Research Laboratories, Inc. has introduced an economical flow through conductivity monitor (Model ICM-180) which can help optimize the separation and recovery of proteins using both classical column and HPLC systems. The conductivity cell attaches to the eluent end of the column and digitally displays conductivity during a run. It has a dead volume of less than 20 microliters, insuring that no remixing of the separated components will occur as well as being totally biocompatible. It also has a broad conductivity range to accommodate most salt gradients and attaches directly to any strip chart recorder for a record of the conductivity profile. The conductivity monitor is also useful for the quick regeneration of ion exchange columns. Lazar has also recently introduced a flow through pH monitor (Model FTPH-1A) for chromafocusing applications.

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