Table 1.

Oxidation of Met34 of mAb A following 4- and 18-hour digestion in conventional LC-MS.

Sample	4 Hr digestion	18 Hr digestion
−80°C	0.5%	0.9%
−40°C	0.5%	0.8%
5°C	0.7%	1.9%
25°C	0.6%	1.0%

Note: samples were stored at indicated temperatures for 12 months.