Enabling highpurities and yields in therapeutic peptide purification using multicolumn countercurrentsolvent gradient purification
A therapeutic peptide was purified using multicolumn countercurrent solvent gradient purification (MCSGP) chromatography and its performance was compared to the performance of an optimized batch process in terms of yield, purity, productivity and solvent consumption. MCSGP simultaneously achieved high yield and purity while batch chromatography had to trade-off between these performance parameters. Using a single step preparative batch chromatography, product with a purity exceeding 97.0% could only be obtained with a yield lower than approximately 75%. For a final purity of 98.7% MCSGP showed a four-fold yield improvement (19% to 94%), a 10-fold increase in productivity (from 3 g/L/h to 30 g/L/h) and a decrease of the solvent consumption by 70% (from 3.5 L/g to 1.0 L/g).The results also showed the importance of gradient selection to obtain MCSGP parameters delivering a constant impurity profile from cycle-to-cycle.
Today, many therapeutic peptides for pharmaceutical applications are produced by chemical solid phase synthesis. Since this technique involves the execution of many chemical steps without the ability to conduct intermediate purification, the crude product may contain many impurities which are closely related to the main product, such as omission of one amino acid or stereoisomers at one or more chiral centers. Reverse phase chromatography offers a powerful and scalable purification technology that is capable of separating the product from related impurities at a reasonable throughput. However some impurities have very similar properties to the product, and the resolution of the product and the impurities becomes worse when the load is increased. Generally, under preparative conditions, overlaps of the product and closely eluting impurities are observed in the peak front and in the tail. Product pools including the overlapping regions may not fulfill the purity specifications, and may require a narrower pooling range.
By narrowing the pooling range and discarding the product in the overlapping regions, the product yield is reduced. T ...