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A simple SFC/MS (Supercritical Fluid Chromatography/Mass Spectrometry) method set was developed to effectively screen separations of various crude synthetic peptide products of pharmaceutical interest. Additives to the modifier methanol which were successful for these separations were found to include TFA (trifluoroacetic acid) and ammonia mixed with TFA, each at 0.1 % (v/v) composition in methanol. A final screening column set consisted of 2-ethylpyride (2-EP), 4-ethylpyridine (4-EP) and cross-linked diol (Luna™ HILIC) stationary phases. Small, linear and macrocyclic peptides with fewer than ten residues could all be eluted with good performance under at least one of the method conditions comprising the final screening protocol. For larger peptides either the 4-EP and HILIC columns with the above additives provided a good initial screening method set without 2-EP. The gradient was slightly longer and shifted to higher polarity relative to the gradients for smaller peptides. This method was often successful to elute large, hydrophilic peptides up to a 41-mer with acceptable peak profiles although the largest peptides with most ionizable residues were most challenging. For these peptides generally HILIC column performance was better with TFA + ammonia in the modifier than with TFA, while 4-EP performance was usually improved with TFA relative to TFA + ammonia., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Molecular interactions between collagen and chitosan (CC) have the potential to produce biocomposites with novel properties. We have characterised the molecular interactions in CC complexes by viscometry, wide angle X-ray scattering and Fourier transform infrared spectroscopy. It was found that CC are miscible at the molecular level and exhibit interactions between the components; X-ray diffraction of CC blends indicate that the collagen helix structure is lost in CC films with increasing chitosan content. Non-linear viscometic behaviour with decreasing chitosan content is interpreted as evidence of a third structural phase formed as a complex of CC. The blending of collagen with chitosan gives the possibility of producing new bespoke materials for potential biomedical applications.