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Topic: Fluorescence  (Read 5602 times)

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jay

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Fluorescence
« on: September 07, 2004, 10:23:36 PM »
hey, ive been given the below problem in an assignment and have no idea how to solve it. Please help.  :'(

Prblem: A solution of iodide ions gave a fluorescence reading of 62%T. A 10 ml aliquot of a 0.2 mg/L iodide standard was added to 5ml of the solution. What is the concentration of iodide in the solution if the fluorescence intensity of the spiked solution was 84%T?

i know i must use the formula

F= 2.303.K.0.P.E.b.c

where F= fluorescence
         K= Fraction of emitted radiation being  
              collected, usually 90 degrees
         O= fraction of species in sample which
              deactivates to yield the measured emission.
         b= light path
         c= concentration
         E= molar extinction coefficient
         p=incident radiation

any help would be great.

thanks

Offline Mitch

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Re:Fluorescence
« Reply #1 on: September 08, 2004, 01:25:46 AM »
Maybe just Beer's law will do it for you?
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Demotivator

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Re:Fluorescence
« Reply #2 on: September 08, 2004, 10:39:44 AM »
It's a standard addition problem
The ratio of intensities is proportional to the ratio of concentrations so
Funk/F unk+std = conc unk/conc unk+std
where
conc unk+std
= (Vi/Vf)(conc unk) +(Vi/Vf)(conc std)
solve for conc unk

Only, I don't know why you have %T implying transmittance instead of F.

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