Set-up of large laboratory-scale chromatographic separations of poly(ethylene glycol) derivatives of the growth hormone-releasing factor 1–29 analogue

In this paper we report the scale-up of the purification of poly(ethylene glycol) (PEG) derivatives of the growth hormone-releasing factor 1–29, from laboratory scale (100 mg of bulk starting material) to larger scale (3 g of bulk), through the use of a cation-exchange TSK-SP-5PW chromatographic column. A one-step purification process capable of purifying large amounts of mono-PEGylated GRF species from the crude reaction mixture was developed. A simple, straightforward stepwise gradient elution separation was developed at laboratory scale and then scaled up with a larger column packed with a chromatographic resin with the same chemistry which maintained the laboratory-scale separation profile. Active material recovery and material purity remained constant through the scale-up from the 13-μm stationary phase to the 25-μm larger column. Overall, the gram GRF equivalent/batch process scale showed to be quite reproducible, and could be considered as a good platform for scale up to production scale.