and Circular Dichroism (CD) Spectroscopy FTIR and CD spectroscopy were used to screen for gross structural changes in the BSA formulations before and after heating and following the addition of polysorbate 80. No significant changes were observed in the peak positions or intensities in the FTIR spectra (Figure ) or the CD spectra (Figure ), when either the formulations with or without polysorbate 80 were heated. The FTIR spectrum of neat BSA was in good agreement with that presented in the work of Quing et al. . Significant differences were observed between the lyophilised BSA formulations and the samples of neat BSA as received from the supplier. The lyophilised formulations included additional peaks in the region 900 1200 cm 1 , which were attributed to sucrose. Notably, the interaction between the excipients and the protein under investigation, can cause a shift in the protein peak positions and shapes, and thus a linear excipient subtraction will reduce the effects of the excipients on the spectrum, yet will not completely remove all the excipient related peaks.