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Design of a chemical reactor

  1. Jun 28, 2007 #1
    Hi,

    I am trying to do a experiment on artificially induced hibernation of mice. I am trying to send 80ppm of a hibernation inducting substance in the atmosphere of the mouse cage. The compound is H2S which is generally toxic but completely safe at these levels. H2S is gaseous at -60 degrees Celsius and above but can be dissolved in water.

    I am looking for ideas and suggestions on how to setup a system that will outgaz 80ppm (but ideally tunable from 0-200ppm) into a isolated hermetic mouse cage.
     
  2. jcsd
  3. Jun 28, 2007 #2

    Bystander

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    500 ppm is a literal "knock-down" concentration --- paralyzes you so quickly you stop breathing before it reaches the lungs --- actually "safer" than 200 --- you can be resuscitated from the knockdown, whereas, any time at 200 loads your bloodstream sufficiently that you are "daid, daid, daid."

    Check your concentrations and exposure times before doing such things to a poor damned mouse.
     
  4. Jun 28, 2007 #3
    Your tone isnt very friendly. You should probably have done a little bit research before posting this as the research as already been done and published. and it works I am just stating what they did. 80ppm does exactly what I mentionned. I know what it does what I did and the mouse are reanimated whit no injury. Please don't turn this treat into a flame war as it is obvious you have no idea what happens at 80ppm. Additionnaly I am really looking forward to an answer to my question so please don't let this treat derail any further.
     
  5. Jun 28, 2007 #4

    chemisttree

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    I would use sodium sulfide and acid. The sulfide is easily weighable and so standard solutions can be safely stored and carefully added by syringe. Addition of this to an acid solution (I would use sulfuric or phosphoric) should easily generate the levels in a controllable fashion. Use an aquarium pump inside the sealed cage attached to an airstone to mix and sparge the H2S into the atmosphere.

    Research and understand the explosive limit for H2S and never load sufficient amounts of sodium sulfide to generate that into your syringe.
     
  6. Jun 28, 2007 #5

    russ_watters

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    There was nothing wrong with Bystander's tone. That was just a few matter-of-fact statements and some opinion. This forum has a no BS tone that some new users may not be used to.
     
  7. Jun 28, 2007 #6
    Very good reply chemisttree. Can you confirm if this is what you had in mind?
     

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  8. Jun 28, 2007 #7
    Ah! point taken I will try to get used to it :)
     
  9. Jun 28, 2007 #8
    Alex, you said the gas is "completely safe at these levels" and that you want those levels to be "tunable from 0-200ppm". I think it's very important to note (in a more stern than plain friendly manner) how close or far this range is from being toxic, and even more important if it really so happens that a completely fatal level is inside the range that you call ideal.

    And even if you already knew "all that", many others reading this thread later on will not. (One normally wouldn't expect any real scientist to turn to the internet for instruction constructing a dangerous research apparatus.)

    It's also worth pointing out that experiments cannot normally be done using animals (especially mammals such as you are intending) without ethics committee approval. In your case, as you claim "the research [h]as already been done and published", one has to wonder what further benefit there could possibly be to justify subjecting mice to this same treatment (and risks) yet again?
     
  10. Jul 2, 2007 #9
    Cesiumfrog,

    I am doing it again because the published work only did it one time on the animal. I want to see if it can be applied periodically and how the mouse will respond to that. No commitee are required for mouse lab work. It is the only animal not covered by any animal protection right in the US and canada. not that anyone should abuse that.. just makes it easier to start a small business if its not required to set up a comittee

    Ill also mention that I contacted the author and asked him if what I intend to do was already done but not published. He has never answered.
     
    Last edited: Jul 2, 2007
  11. Jul 3, 2007 #10

    chemisttree

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    That would work but you should know that there is no reason to place the acid/sulfide solution inside the cage. The air lines can be routed through an external supply of these. It facilitates cleaning, fixing mistakes and prevents the animal from coming in contact with the solution. You should know that any metals (including stainless) will severely corrode in this atmosphere. The pump shouldn't last for long.
     
    Last edited: Jul 3, 2007
  12. Jul 3, 2007 #11

    chemisttree

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    I am amazed that H2S has this property given the presence of wide awake rats in many sewers. Could someone please point to some research that indicates that this effect has been observed?
     
  13. Jul 3, 2007 #12
  14. Jul 3, 2007 #13

    chemisttree

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    Thanks. This type of chamber has been devised for the study of the deterioration of concrete by H2S-fed thiooxidans bacteria. LaFarge has built one of these chambers in Germany and several other researchers have built them in the US. The chambers are described in modest detail in the literature by these authors.
     
    Last edited: Jul 3, 2007
  15. Jul 5, 2007 #14
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