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From: Jason Fritz <lokster.jf**At_Symbol_Here**GMAIL.COM>
Subject: Re: [DCHAS-L] Old Bleach
Date: Mon, 25 Oct 2021 16:05:18 -0600
Reply-To: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID: CAPc8KTVBwowkYhCpw8Vs=kupiCPZ17j4BA9nytHOdQN+wzVPjA**At_Symbol_Here**mail.gmail.com
In-Reply-To

Demystify: 

Hello Patricia,
For long-term experimental studies, we had to prepare and track HOCl concentrations in solution over time, which was quite easy to do by measuring the absorbance at 292nm using a standard UV/Vis instrument. This may not work due to interference in complex buffers, but in simple aqueous systems, it worked quickly and was robust.
It should be fairly easy to prepare a dilution curve from a known stock container, estimate the amount of HOCl present in the old bleach containers, and then dilute as necessary to achieve a desired concentration for disinfection.
Perkin Elmer has a short lab resource sheet describing this method: https://resources.perkinelmer.com/lab-solutions/resources/docs/APP_Quantification-of-Sodium-Hypochlorite.pdf
And there are spectrophotometric alternatives as well, e.g.: https://www.sciencedirect.com/science/article/abs/pii/S0026265X97915423
Best of luck,
Jason

On Mon, Oct 25, 2021 at 3:45 PM Patricia Leach <Patricia.Leach**At_Symbol_Here**tamuc.edu> wrote:

Hello,

I was wondering about using old stocks of bleach for disinfecting in bio labs. The bleach is about 2 years old and has never been opened. I am not sure if it is industrial or commercially available bleach. Any advice would be appreciated.

Patricia Leach

Environmental Health and Safety Coordinator

Emergency Management and Safety

Texas A&M University - Commerce

P: 903.468.3278

C: 316.644.8255

Mail: P.O. Box 3011, Commerce, TX 75429

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