Ascites. When ascites is reconstituted by addition of water, we usually add small amounts of azide or thimerosal to prevent microbial growth. Ascites should be stored frozen. Monoclonals usually do not suffer from repetitive freeze-thawing but you may aliquot them into small samples to avoid too many freeze-thaw cycles.
Prolonged storage at 4°C is not recommended! Unlike serum, ascites may contain proteases that will ultimately degrade the antibodies. Addition of protease inhibitors helps to slow degradation.
Purified IgG. Do not store diluted antibody solutions unless you add detergent or carrier proteins such as goat serum, BSA or others. IgG sticks to glass and plastic. Any IgG solution below 0.1 mg/ml protein will quickly adsorb and denature and thus loose activity! Repetitive freeze-thawing of dilute purified IgG is almost certain to lead to substantial losses