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10% bleach solution confusion Options
 
blue.magic
#1 Posted : 1/3/2018 7:45:11 PM
I've read numerous times, that one should use "10% bleach solution" to disinfect glove boxes, inoculation area etc.

However, what is sold as "bleach" (e.g. Clorox) is already a 10% solution of sodium hypochlorite.

Does it mean I have to further dilute this in 9 parts water effectively having 1% sodium hypochlorite solution? Or 10% bleach means 10% sodium hypochlorite solution so no further dilution is needed?

I have a 12% NaClO solution so I don't know if I can use it right away or further dilute...
 
Ulim
#2 Posted : 1/3/2018 8:47:58 PM
 
Godsmacker
#3 Posted : 1/3/2018 9:39:40 PM
This document may be of use to you, as it discusses safe dilution amounts (e.g. 1:100 dilution factor of 5% NaClO to water--a 1:200 ratio in your case. This document may also be of use for making sanitization solutons of NaClO.

For simplicity's sake, I'd suggest doing these calculations/dilutions assuming that your stock solution of NaClO was 10% by mass/volume (I'd suggest you also make sure that it just contains NaClO, water,and no other potentially harmful contaminants which don't evaporate at a reasonably fast rate at room temperature). Making safer-to-use dilute sterilization/sanitation solutions from concentrated NaClO doesn't require much attention to detail. Such gross approximations when diluting would suffice. So as long as you take proper safety precautions, wash your surfaces/environments thoroughly with distilled/deionized water afterwards, and that what you're cleaning doesn't contain any species and/or environmental conditions which may form harmful substances and/or reactions when combined with NaClO (e.g. peroxides, alcohols, ammonia & nitrogenous derivatives thereof, acids which drop the pH below 2, acetone, excessive heat and light, exposure, etc.), you should be fine.

I would recommend you use a dilute solution when cleaning in lieu of the stock solution itself, as using the latter would be far more dangerous to your health, be more expensive per use, would most likely be just as effective at cleaning/sterilizating/sanitizing surfaces/environments as a dilute solution, and may be more harmful/rough on your surfaces than a dilute solution would be (many many many substances/surfaces don't play well with NaClO at all.) One should strive to dilute it to the point where it would be an effective cleaning agent whilst posing as little threat to your health & surroundings as possible. It's easy to make chloroform, volatile chloramines, chlorine gas, explosions and many other day/life-ruiners with NaClO. I can't stress safety precautions enough...

As an aside, "bleach" is a very crude and ubiquitous term to describe solutions of various hypochlorite salts. I refer to my "bleach" as a concentrated 8.25% hypochlorite solution, as I don't have the time to dilly-dally with such a trivial name (yet ironically enough have enough time to smear this rant all over your thread). I hope this rip-tide of information is of use to you.

Stay safe,
-God
'"ALAS,"said the mouse, "the world is growing smaller every day. At the
beginning it was so big that I was afraid, I kept running and running, and I was glad
when at last I saw walls far away to the right and left, but these long walls have
narrowed so quickly that I am in the last chamber already, and there in the corner
stands the trap that I must run into." "You only need to change your direction," said
the cat, and ate it up.' --Franz Kafka
 
pitubo
Senior Member
#4 Posted : 1/3/2018 10:07:20 PM
Household bleach is typically a 5% sodium hypochlorite solution, stabilized with sodium hydroxide.(*)

So, 10% bleach is a 0.5% sodium hypochlorite solution.

Be careful, because apart from the bleaching (oxidizing) action of the sodium hypochlorite, even after dilution the solution is still appreciably alkaline due to the sodium hydroxide.

(*) Sodium hydroxide is added to keep the solution alkaline. If the pH drops below 7, hypochloric acid is formed, which is much less stable. If the pH drops much lower even, toxic chlorine gas could be released.
 
blue.magic
#5 Posted : 1/3/2018 11:51:40 PM
Ulim wrote:
http://www.who.int/ihr/publications/Annex7.pdf
first result when googling


I have probably used different keywords than you.
The articles I read made me only more confused.

But I admit I was lazy...

Godsmacker wrote:
As an aside, "bleach" is a very crude and ubiquitous term to describe solutions of various hypochlorite salts.


I am not using household bleach, but "sodium hypochlorite, 12%" from chem supplier, which states the solution is "at least 12% sodium hypochlorite".

The sources on the net uses the term "bleach" which is of course confusing and the composition depends heavily on the brand.

Okay so I will make 1% w/v NaClO/H2O solution using distilled water from 12% w/v NaClO/H2O and wash the treated surfaces with fresh distilled water.
 
 
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