April 19, 2024, 01:13:32 PM
Forum Rules: Read This Before Posting


Topic: Molar absorption coefficient (e) dependens on...  (Read 10507 times)

0 Members and 1 Guest are viewing this topic.

Offline Homer Jay

  • Regular Member
  • ***
  • Posts: 21
  • Mole Snacks: +0/-0
  • Gender: Male
Molar absorption coefficient (e) dependens on...
« on: December 30, 2007, 05:21:26 PM »
Hello,

does the molar absorption coefficient depend on the photometer used for measurement?

Is it possible, that the absorbance of a solution measured on one photometer is not equal to the absorbance of the same solution on another photometer?

Thanks in advance,

Homer

Offline Borek

  • Mr. pH
  • Administrator
  • Deity Member
  • *
  • Posts: 27652
  • Mole Snacks: +1800/-410
  • Gender: Male
  • I am known to be occasionally wrong.
    • Chembuddy
Re: Molar absorption coefficient (e) dependens on...
« Reply #1 on: December 30, 2007, 06:38:07 PM »
does the molar absorption coefficient depend on the photometer used for measurement?

No.

Quote
Is it possible, that the absorbance of a solution measured on one photometer is not equal to the absorbance of the same solution on another photometer?

Yes.

Think about calibration - why do we do it? Think about instrument sensitivity and all factors that can change it.
ChemBuddy chemical calculators - stoichiometry, pH, concentration, buffer preparation, titrations.info

Offline ARGOS++

  • Sr. Member
  • *****
  • Posts: 1489
  • Mole Snacks: +199/-56
  • Gender: Male
Re: Molar absorption coefficient (e) dependens on...
« Reply #2 on: January 02, 2008, 02:40:59 PM »

Dear Homer Jay;

Epsilon!  ─  The Molar Extinction Coefficient is a material constant which depends on a lot of parameters, most people don’t really care of.
That’s precisely why most ask again, and again, for numeric values without any care for all the experimental and measuring parameters, like solvent, mixture, pH, etc., and also not care for reliability and validability of all.

To get a minimal Idea for “all” of the dependencies, and why the already mentioned calibration is really indispensable/requisite, you may read in the rubric: “References” on the page:
(Now you will also know, of what putative value all this published Atlases are.)

Additionally quite a lot of mistakes are made by transferring such methods from one Spectrometer to another, in case the calibration is not repeated.

I hope this may be already of help to you.

Good Luck!
                    ARGOS++


Offline Homer Jay

  • Regular Member
  • ***
  • Posts: 21
  • Mole Snacks: +0/-0
  • Gender: Male
Re: Molar absorption coefficient (e) dependens on...
« Reply #3 on: January 06, 2008, 05:03:32 AM »
Thank you for your answers.

Very interesting homepage ARGOS++ !

Sponsored Links