We are interested in collection of ascites for protein analises. I would like if you know a protocol for storage of this fluid till the analises.

You can store ascites fluid (or the ascites fluid/PBS mix) with 0.1%azide in single thaw aliquots in -20dC. The aliquots must be of a size that you expect to finish in about 3-4 weeks of storage at +4dC.