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Topic: Literature values for extinction coefficients?  (Read 8085 times)

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Offline Liverspots

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Literature values for extinction coefficients?
« on: November 22, 2012, 08:59:45 AM »
I've been struggling to understand extinction coefficients, ε, for a thermal lens calorimetry experiment I am working on.

I've used my lab data to calculate ε using the formula ε = (ΔBeam Intensity/Initial Beam Intensity)/(E*b*c*2.303). That seems to be fine. But I want to a % error comparison with the values I am producing and I'm having trouble locating a good source (specifically online, but print will work in a few more days).

To be specific I need to located ε for:
Indophenol in methanol
Trypan blue in methanol
Bromophenol blue in acetone
Bromophenol blue in water
Bromophenol blue in methanol

Thank you for any advice you are able to share.

Offline Arkcon

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Re: Literature values for extinction coefficients?
« Reply #1 on: November 24, 2012, 01:07:03 PM »
You could try Googling for your terms. Several years ago, there was a webpage, made by someone, that had the excitation and emission max (fluorescence) for a number of biological stains and similar dyes.  But I don't know of comprehensive, well-maintained lists.  This webpage was just someone with some knowledge and some free time on their hands to code it all in a web page.  There may be better things available, but there may also be no interest in hosting such data.
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline MOTOBALL

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Re: Literature values for extinction coefficients?
« Reply #2 on: November 25, 2012, 11:51:49 AM »
                                                λmax           log ε

Indophenol (MeOH)                     262            4.19
                                                 314            3.97
                                                 503            3.93

Bromophenol Blue (water)           440            3.48
                                                 600            4.82

Ref. CRC Handbook of Chemistry & Physics, 59th Ed. 1978-9. (only those solvents)

I'm working on Trypan Blue.


Offline Liverspots

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Re: Literature values for extinction coefficients?
« Reply #3 on: November 25, 2012, 01:41:05 PM »
Thank you for what you've been able to find. Does the extinction coefficient of a solution vary by what solvent is used? I suspect it does but I am not 100% sure.

Offline Babcock_Hall

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Re: Literature values for extinction coefficients?
« Reply #4 on: November 25, 2012, 05:08:55 PM »
Sometimes only the λmax shifts with a change in solvent, but I believe that there are cases where both ε and λmax shift.  You might look up bathochromic or hypsochromic shifts.

Offline Arkcon

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Re: Literature values for extinction coefficients?
« Reply #5 on: January 18, 2013, 09:56:52 PM »
Digging through some old bookmarks, I found one of the pages I mentioned.  Click on the Dyes tab and see if you can find the sort of information you might need.  http://stainsfile.info/StainsFile/jindex.html
Hey, I'm not judging.  I just like to shoot straight.  I'm a man of science.

Offline Time_sama

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Re: Literature values for extinction coefficients?
« Reply #6 on: July 09, 2020, 01:42:07 PM »
                                                λmax           log ε

Indophenol (MeOH)                     262            4.19
                                                 314            3.97
                                                 503            3.93

Bromophenol Blue (water)           440            3.48
                                                 600            4.82

Ref. CRC Handbook of Chemistry & Physics, 59th Ed. 1978-9. (only those solvents)

I'm working on Trypan Blue.

Hi, sorry for the very late answer, but I needed this data in the research and it seemed strange for me. Couldn'd find these in CRC (my bad), so I checked it myself.
For BPB the ε in water at 438 nm is 24429 ±1100, at 591 nm is 86317 ±5983
The range of concentrations from 10-5 to 10-6 at pH 2 and 11 respectively
It seems for me that at CRC the ε for BPB is given for MeOH, as I received
For BPB the ε in MeOH at 424 nm is 3501±1133, at 596 nm is 95959 ±2257
all ε are L mol-1 cm-1
The plots are in the attachment
Kind regards

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