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Absorbance - UV Spectroscopy

  1. Apr 24, 2015 #1
    Hi guys, please can you kindly help me. I am getting an absorbance of over 6.0Abs for my experiment. However, when I am reading posts they mention that an absorbance above 1 is not reliable. Please can you explain so that I can understand. Thanks
  2. jcsd
  3. Apr 25, 2015 #2


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    Staff: Mentor

    What it is that you don't understand here? It is hard to help on a dry facts not knowing why you have problems with them.

    Generally speaking to measure that high absorbance you would need to be able to accurately measure intensity of radiation over 6 orders of magnitude, that's not trivial.
  4. Apr 25, 2015 #3


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    An abosorbance value of 6.0 means that if you shine a light through the solution, only 0.0001% of the light passes through. Because it's difficult to accurately measure such a tiny amount of light, the absorbance values are not very reliable. To measure the absorbance of the solution, you should first dilute your sample so that the absorbance falls within a reliable range (generally ~ 0.1-1.0).
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