Development of a comprehensive approach for performance evaluation of a quantitative multi-attribute method as a quality control method.

The multi-attribute method has been recognized as an elegant quantification tool for post-translational modifications (PTMs) of therapeutic proteins, since it can evaluate several attributes spontaneously and site-specifically. Here, the abundance of PTMs calculated by three different types of formula were compared and there was little difference among the results. For the method evaluation, two different kinds of peptides were used as internal standards (ISs) and one of the IS was used as the "standard peak" to define the signal strength of MS. They are also used for system suitability testing to verify whether the condition or sensitivity of mass spectrometry are high enough to evaluate the minor components by confirming the recovery rate of one IS to the another. This system is beneficial that since we have defined the limit of quantification as a certain ratio to IS, consistent MS intensity is applied as the threshold across all detected peaks.