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FTIR:What is the proper instrument for liquid samples?

  1. Feb 15, 2012 #1
    Hi everyone;
    I read some of FTIR threads in forums and they were at the different parts of forums so I decided that it's the best place for this question. But if I am wrong please move the thread.
    I'm new for FTIR measurements. First of all I want to say that I'm doing this kind of measurements only for scientific purpose.

    I use an FTIR machine which operates under vacuum. I tried a holder/instrument but it is not useful due to the fact that it has no transmission at some wavelengths.
    What kind of holder/instrument are you using to measure liquid samples under vacuum?
    Where can I find these holders/instruments?
    Thanks for your help.
     
  2. jcsd
  3. Feb 15, 2012 #2

    cmb

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    I've not used the FTIR at work but as far as I see the kit used it comes with some form of small transparent pucks that are for the purpose. Can't say what they are made of, they come with the kit. I think it is some form of inorganic salt. You put a drop of liquid on one, then put the other on top. You get a film of the liquid between the two pucks and they [are made to the right size to] fit in a demountable cell that slots into the analysing channel of the machine.

    Edit; something like... http://www.perkinelmer.com/Catalog/...able Cell and Cell Parts for 1600 Series FTIR

    ..windows for same; http://www.perkinelmer.com/Catalog/Family/ID/Circular Demountable Cell Windows for 1600 Series FTIR
     
    Last edited: Feb 15, 2012
  4. Feb 15, 2012 #3
    I'm reading one of the links. Thank you for your help. I really appreciate it.
     
  5. Feb 15, 2012 #4
    I worked with an IR spectroscopy group 12 years ago and the cell windows were NaCl and CaF2. We ran spectra with both because IR absorption patterns were different for the two salts. The windows are hard to clean. The NaCl especially tends to absorb water and requires a special polishing kit. Also, we used to inject liquid samples with a syringe and clean the cells between spectra by blowing air through them, a technique that worked in our case because the liquids used (bromobenzene derivatives) were highly volatile. So, in a nutshell, you can expect to need different cell windows. I used the CaF2 whenever possible because it was less hygroscopic and then used NaCl to cover wavelengths absorbed by the CaF2 window.
     
  6. Feb 26, 2012 #5
    Thank you for the answer and also for sharing your experience. It helped a lot.

    I have one more question,
    Is it a good choice to measure in ATR mode instead of using these cells?
    Could I get same spectrum quality with this method? I mean in ATR mode.
     
  7. Mar 2, 2012 #6

    chemisttree

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    Thermo Scientific has one in their accessory catalog. Item number 0030-101.
     
  8. Mar 2, 2012 #7

    chemisttree

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    ATR is best for neat or very concentrated samples. I've never seen an ATR fixture for vacuum though.
     
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