absorbance and concentration

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biology_06er
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absorbance and concentration

Post by biology_06er » Mon Sep 17, 2007 10:18 am

Hi there,

Can someone please explain how to calculate the conc. from just an absorbance reading and concs. oofvarious substances in say molNADH/Lmin?

Cheers,
biology_06er

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canalon
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Post by canalon » Mon Sep 17, 2007 5:15 pm

formula:
http://en.wikipedia.org/wiki/Beer-Lambert

as for your results it won't be in mol NADH/L /min because it will be in mol (substance which concentration is measured)/L at the time the measurement is done. To have the minute part you have to do repeated measurement at different recorded time and calculate the variations by yourself.

Hope this helps
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

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Post by biology_06er » Tue Sep 18, 2007 6:25 am

Hey there,

:? ..yeah I was thinking of using beer's law seeing as we were given a "E" value..but im still unsure what to do..we only did the experiemtn once got an ab. reading...the eq=ethanol+NAD+--->acetaldehyde +NADH + H+

so i have to figure out molNADH/L/min...

I have abs/min (A) (i calc. from my graph) so does this mean I just go..using say values of A=3 E=2 C=? and L=1

A=ECL
C=A/EL
C=3/2X1

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canalon
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Post by canalon » Tue Sep 18, 2007 3:44 pm

Correct. You just need to convert the Abs in concentration with Beer-Lambert's equation.
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)

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