## absorbance and concentration

Debate and discussion of any biological questions not pertaining to a particular topic.

biology_06er
Coral
Posts: 260
Joined: Tue Mar 21, 2006 9:33 am

### absorbance and concentration

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

canalon
Inland Taipan
Posts: 3909
Joined: Thu Feb 03, 2005 2:46 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)

biology_06er
Coral
Posts: 260
Joined: Tue Mar 21, 2006 9:33 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

canalon
Inland Taipan
Posts: 3909
Joined: Thu Feb 03, 2005 2:46 pm