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Starspawn
NotGoodJustLucky
Registered: 07/25/02
Posts: 98
Loc: ShowMeState
Last seen: 20 years, 29 days
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Why check H2O2 concentration
#834495 - 08/21/02 07:49 PM (21 years, 7 months ago) |
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Could anyone post how to measure peroxide concentration.The reason I need to know is because i can get peroxide in bulk for cheaper.Swimming pools use a much stronger concentration,so does restaurant grade.Other then that I would also like to make sure the H2O2 I put in storage stays as strong as i mixed it.So, if anyone knows how to measure peroxide concentration, please post.
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Macey Howard
Formally MOE HOWARD
Registered: 07/02/99
Posts: 14,165
Loc: Georgia
Last seen: 7 years, 6 months
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Post deleted by Moe Howard [Re: Starspawn]
#834916 - 08/22/02 03:06 AM (21 years, 7 months ago) |
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-------------------- Hugs and Kisses!
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mycofile
Pooh-Bah
Registered: 01/18/99
Posts: 2,336
Loc: Uranus
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Re: Why check H2O2 concentration [Re: Macey Howard]
#835057 - 08/22/02 04:16 AM (21 years, 7 months ago) |
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Funny moe, but peroxide concentration varries from whats on the label, not to mention degrades in storage.
the other day I posted the general procedure but left out some details I needed to check the manual for. I'll try and get them tonight. Basically, you degrade the peroxide with a bannanna, catch the oxygen it produces, and measure the oxygen. The amount of oxygen you get tells you exactly how much peroxide there was to begin with.
If you are a smart chemistry minded person, you should be able to figure out how much oxygen X amount of peroxide produces when it breaks down, but I don't know how off the top of my head.
-------------------- "From a certain point of view" -Jedi Master Obi Wan Kenobi PM me with any cultivation questions. I just looked at my profile and realized I had a website at one point in time on geocities, it's not there anymore and I have no idea what I had on it. Anybody remember my website from several years aga? PM if so please.
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nonsence
friend
Registered: 07/15/02
Posts: 58
Loc: Australia.
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Re: Why check H2O2 concentration [Re: Starspawn]
#835411 - 08/22/02 07:11 AM (21 years, 7 months ago) |
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the Wayne book, Growing Mushrooms the Easy Way Home Mushroom Cultivation with Hydrogen Peroxide contains in detail the procedure mycofile mentioned.
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Champion des Champignons
long standing member;)
Registered: 07/26/00
Posts: 2,680
Loc: Alba
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Re: Why check H2O2 concentration [Re: mycofile]
#835889 - 08/22/02 11:37 AM (21 years, 7 months ago) |
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hydrogen peroxide solution will produce 10 times its volume of oxygen for every 3%, so eg. 10ml of 9% solution will produce 300ml of oxygen when completely denatured.
-------------------- --------------------------------------------------- hmmm........
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Suntzu
Geek
Registered: 10/14/99
Posts: 1,396
Last seen: 17 days, 5 hours
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Re: Why check H2O2 concentration [Re: nonsence]
#835939 - 08/22/02 11:57 AM (21 years, 7 months ago) |
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I remember Rush's technique involved a balloon wrapped over a 'test tube' that contained the peroxide solution. Personally, I really like the banana idea. Banana flesh would certainly break down peroxide! Better than just shaking, which is what I think Rush described.
The pharmacy-grade peroxide, the stuff they say is "3%" does indeed vary widely in its actual percentage. Once you get up into higher concentrations, the quality control is a little better [as it needs to be for industrial processes]. When I buy peroxide that is labelled at "30%", I trust it. Usually hasn't been sitting on a shelf, temp fluctuations, etc.
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Alkaloids
3,4,5-trimethoxyphenethylamine
Registered: 11/15/98
Posts: 743
Loc: pubis mons
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Re: Why check H2O2 concentration [Re: Suntzu]
#836358 - 08/22/02 02:48 PM (21 years, 7 months ago) |
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where do you order your peroxide from Suntzu? I was looking for a good resource. PM if you think that would be better. thank you
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mycofile
Pooh-Bah
Registered: 01/18/99
Posts: 2,336
Loc: Uranus
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Re: Why check H2O2 concentration [Re: Alkaloids]
#836433 - 08/22/02 03:20 PM (21 years, 7 months ago) |
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But post it here unless you really need to keep it private.
The bannanna idea wasn't mine. It very well may have been rush's. I'm sure he recomended a biological breakdown of it though, not just shaking it.
And for those that couldn't figure it out, the balloon can be emptied into a graduated cylinder wich is inverted full of water while under water. The oxygen displaces the water, and you just measure the cc's.
enjoy
-------------------- "From a certain point of view" -Jedi Master Obi Wan Kenobi PM me with any cultivation questions. I just looked at my profile and realized I had a website at one point in time on geocities, it's not there anymore and I have no idea what I had on it. Anybody remember my website from several years aga? PM if so please.
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tchyted
miestro
Registered: 09/03/01
Posts: 526
Loc: WA near seattle
Last seen: 9 years, 6 months
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Re: Why check H2O2 concentration [Re: Starspawn]
#840380 - 08/24/02 10:44 AM (21 years, 7 months ago) |
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i own both of Rush's manuals.
he in fact reccomends using biologicaly breaking down the peroxide.
i did it the first time i used his manual. i came to the conclusion that the measurement tek was fraught with inaccuracy, too much pittling around.
i buy my peroxide from the same place in the same size container, same brand.
the place i buy from sells a lot of it, and rotates their stock continuously.
once you familiarize yourself with using peroxide, you will be able to tell that you have the correct concentration by the way that it behaves in use.
while the concentration from the supplier varies widely, there is also a wide window of concentration that is acceptable to use, and all one needs to do is assure that he is inside the window.
i have since stopped trying to measure concentration quantitativly and simply measure it objectivly. good peroxide will foam at a predictable rate when applied to a biological substance that contains the correct enzymes. that's all the measuring you should really need.
while use of peroxide has certainly changed mushroom cultivation forever, one should not rely entirely on it, as it is not the whole answer.
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mycophreak
journeyman
Registered: 05/29/02
Posts: 50
Loc: Europe
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Re: Why check H2O2 concentration [Re: Starspawn]
#841533 - 08/25/02 12:33 AM (21 years, 7 months ago) |
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Buying peroxide in bulk is not a good idea since it decays. Buying it fresh in small bottles is much better. I do not think it will be more than a buck or two per 100ml bottle of 3 percent strength, which will be enough for many hundreds of agar plates.
For testing I like the empirical test best. I am totally uninterested in the exact concentration. What I want to know is if a given concentration keeps contaminants away in my individual situation. So what I do is make a dozen or so of test plates. Each with a different concentration of peroxide.
When the agar is soldified, I lift the lid from the dishes for 5 minutes. Then I replace it and wait 2 weeks. The dish with the lowest effective concentration is the best. If no dish contaminates I do the same test again but with the lowest concentration of the first test as maximum concentration of the second.
This is a test which only needs to be performed once in each location.
Every time you get a new small bottle of peroxide, you test if that experimentally defined concentration still is OK. If not then double it. In over five years of peroxide experiments I have never seen a mycelium which can not handle twice the minimum effective concentration. Nor have I seen a single contaminant spore surviving it.
Yachaj
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