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Bradford dye absorption spectrum question?

  1. Oct 15, 2014 #1
    View attachment 74483 View attachment 74483
    Based in the absorption spectra above, why is 595 nm the best wavelength to measure protein concentration with Bradford dye (Hint: there are two important reasons for choosing 595).
    I think it has something to do with the color wheel but honestly the explanation in the manual is very unclear. Can someone try to explain it to me?

    Attached Files:

  2. jcsd
  3. Oct 16, 2014 #2
    You are asking a question but provide a hint. Is this homework?

    You had to make me read up on the local roolz: "Helpers: don't provide the entire solution". [ https://www.physicsforums.com/threads/guidelines-for-students-and-helpers.686781/ ]

    I haven't done anything like that, so mind that maybe I'm not helping at all because I could be misunderstanding the procedure.

    FWIW, but after looking around the web I'm guessing the wide separation of peaks between acidic and non-acidic forms of the dye is part of one of the two reasons. The other reason could be related to that, by the quantitative use of the absorption measurements, taking ratios (which may or may not be called a "modified" assay - here is where I would urge caution based on my unfamiliarity with the subject).

    Now why would I make those two guesses?
  4. Oct 20, 2014 #3

    Andy Resnick

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    It's pretty clear from your spectra. Echoing Torbjorn, why are you providing 'hints'?
  5. Oct 20, 2014 #4
    I have an unquenchable thirst for chemical research over the best or optimal wavelength to measure the blue color represented as a global maximum. :DD
    Last edited: Oct 20, 2014
  6. Oct 21, 2014 #5
    In case this is homework:

    Since I posted my previous comment, I have noticed that (not attempted) homework has another place.

    "Homework Guidelines
    • Posts Belong in the Homework Forum
    Any and all high school and undergraduate homework assignments or textbook style exercises for which you are seeking assistance are to be posted in the appropriate forum in our Homework & Coursework Questions area--not in blogs, visitor messages, PMs, or the main technical forums. This should be done whether the problem is part of one's assigned coursework or just independent study. The reason for this is that the scientific and mathematical sections of Physics Forums are to be reserved for discussions and not academic assistance. Since graduate level assignments are meant to be more thought provoking (and hence more worthy of discussion), graduate level questions will be allowed in the relevant part of the main section of PF, provided that the graduate student attempts the problem and shows his work."

    [ https://www.physicsforums.com/threads/physics-forums-global-guidelines.414380/ ]
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