Effects of large sample loads on column lifetime in preparative-scale liquid chromatography

In preparative-scale liquid chromatography of proteins, the use of high sample concentration and large sample mass may result in irreversible adsorption to the support surface. This can change the stationary phase characteristics, reduce the capacity, shorten the column lifetime and diminish the economic viability of a particular separation method. Column recycling and regeneration can influence the throughput (mass purified per time unit) and selectivity, and affect the reproducibility. The effects of large sample loads on column lifetime and performance were evaluated for three strong anion-exchange columns: (1) a silica support with a quaternized polyethyleneimine (PEI) coating, (2) a polymeric support with an adsorbed PEI coating which also was quaternized, and (3) a polymeric support with a proprietary quaternary amine stationary phase. The column capacity for proteins was measured by frontal chromatography and monitored as a function of cycle number. The column lifetime was determined by examining chromatographic properties subsequent to the frontal chromatography. The change in protein binding capacity was then compared to the change in nitrate binding capacity. The column performance was evaluated under analytical conditions by measuring the change in resolution of standard protein mixtures.