Circular dichroism (CD) spectroscopy is a well-established technique for the structural characterization of chiral molecules and has become an indispensable part in the biophysical toolbox for biotherapeutics development. Particularly, CD spectroscopy provides information about both secondary and tertiary structure of antibody-based therapeutics, including biosimilars, and as such is essential for controlling higher order structure (HOS) as a critical quality attribute (CQA) within a totality-of-evidence approach.
However, CD data are often still assessed only qualitatively by subjecting spectra to visual evaluation. To eliminate user bias, spectral differences should instead be quantified by a reproducible mathematical approach which eliminates guesswork and scrutinizes results against a well-defined acceptance criterion that informs whether these differences are statistically relevant or not.
