Effective Shelf-Life of Prepared Sodium Hypochlorite Solution

By Johnson BR, Remeikis NA

Date: 01/1993
Journal: JOE


Purpose:   To investigate the variables of storage conditions and time on the tissue-dissolving capacity of three different concentrations of sodium hypochlorite.


-Fresh solutions of sodium hypochlorite were prepared using a readily available source of 5.25% sodium hypochlorite (Clorox bleach).

-Solutions were stored in either translucent or opaque air-tight 250-ml nonreactive polyethylene bottles. The 2.62%     and 1% solutions were prepared by dilution with either tap water or sterile distilled water.

-Tissue samples were prepared from sections of fresh frozen human umbilical cord immersed in a glass beaker containing 20 ml of NaOCl solution. Solutions were stirred every 30 s and the total time required for complete dissolution of the tissue sample was recorded.

– Measurements were made on day 1 and at 1-, 2-, 3-, 4-, and 10-wk intervals.

– pH of each solution was also measured at all time intervals. Room temperature was maintained at 24°C.

Most highlighted Results:

-Concentration of the sodium hypochlorite solution was directly related to the rate of tissue dissolution.

–      Tissue-dissolving ability of 5.25% NaOCl remains stable for at least 10 wk.

–      Tissue-dissolving ability of 2.62% and 1.0% NaOCl remains relatively stable for 1 wk after mixing, then exhibits

       a significant decrease in tissue-dissolving ability at 2 wk and beyond.

Clinical significance:

sodium hypochlorite irrigating solutions should be mixed fresh. However, all solutions at all time intervals had at least some tissue solvent activity.