Preservative Formulation

Why do you use pentochlorophenol? Can I use another preservative such as azide? Can I store your products without preservative?


Enzymes, buffers, and columns in our kits contain 0.5 µg/mL pentochlorophenol as a preservative. This has not been found to interfere with any of the conjugation reactions or adversely affect living cells at normal working dilutions. However, for your application you may want to use a different preservative or none at all.

Sodium azide is frequently used as a preservative and we have not found any interference with conjugation reactions at concentrations up to 0.05%. It is not necessary to remove the pentochlorophenol, just add azide(0.02% - 0.05%). However, azide is toxic to living cells and can inhibit enzymes such as horseradish peroxidase.

To eliminate the preservative, dialyze the enzyme against your new buffer and re-equilibrate the columns with your new buffer to remove the pentochlorophenol. If you choose not to use a preservative, we recommend filter-sterilizing your solutions and storing them aseptically to prevent microbial contamination.