Peptides are extremely stable when stored at -20° C in their lyophilized powder form. We recommend keeping all peptide in its lyophilized state and only reconstituting what is needed for short-term use.
Most of the peptides that we use for generating custom antibodies are reasonably hydrophilic and will dissolve readily in PBS, water or saline solutions. If a small test batch of peptide solubilizes easily in PBS, then we recommend dissolving at a 1 mg/ml concentration to create a working stock of the peptide.
If the peptide isn’t soluble in a PBS buffer, then we recommend first dissolving the peptide in a solvent such as acetonitrile (ACN), dimethylsulfoxide (DMSO), or dimethylformamide (DMF). Once the peptide has dissolved, it can slowly be added to the PBS buffer.