December 22, 2024, 08:37:26 AM
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Topic: How do you acquire a IR spectrum (KBr) with sample lesser than 5 mg?  (Read 3235 times)

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Offline kanonsviel

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I happen to have to acquire some IR spectrum of some sample which I have only very little amount in hand (lesser than 5 mg, oil), it's almost impossible to transfer them onto the KBr film with a capillary tube.

So I'm wondering whether it is possible to dissolve it with a little mount of CH2Cl2 and spread the solution on to the KBr film, wait until the CH2Cl2 to volatilize, and acquire the spectrum?

Has anybody done that before?

Or is there any other tip to do a KBr spectrum with very little amount of sample?

Thanks!

Offline Arkcon

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It really does depend more on your instrument than anything else, and your instrument manufacturer will be ale to help.  For example, on the PE-FTIR that I use, 5 mg of a liquid would easily cover the ATR crystal.  But doing that with a powder might not be enough to insure a clean signal.  And I don't know if your instrument will let you use an IR card, but you may likewise get minimal signal if you all you can do is "stain" a KBr plate, ith a dilute evaporated solution.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline kriggy

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What about mix the solution with KBr and then evaporate it and then make the tablet? Instead of spreading it over KBr film

Offline marquis

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Microscope ftir is the easiest way.  Instruments are expensive and hard to find, though.

Offline Corribus

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ATR or thin solution film seems the best way to go.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman

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