Effects of temperature and flow rate on frontal and elution chromatography of aggregating systems

Abstract

During chromatography, β-lactoglobulin A can aggregate into tetramers, octamers, and dodecamers. Increasing temperature changes relative peak heights and results in peak merging. In the literature, temperature-induced shifts in equilibrium distributions were hypothesized to cause these changes. Using a reaction-separation model, we have shown that an increase in reaction rates in accordance with the Arrhenius relationship also explains the literature data well. When aggregation rates are fast relative to mass transfer rates, there is a loss of resolution between individual aggregates; breakthrough times and retention times of concentration wave fronts and peaks are averaged, resulting in a single front or peak. Conversely, when reaction rates are relatively slow, wave fronts and peaks of individual aggregates are distinct. Scaling up a complex reacting system is difficult because changes in apparently unrelated parameters, such as particle size, flow rate, concentration, and temperature, can all alter effective reaction rates. This study shows that a dimensionless group approach provides a simple method to predict surprising results. Most surprising is that at low temperatures (slow reaction rates) a decrease in flow rate results in a loss of resolution between the aggregates, whereas at high temperatures (fast reaction rates) an increase in flow rate can enhance resolution.