Confusion about determining Trp stock solution conc.

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mtbazz
mtbazz's picture
Confusion about determining Trp stock solution conc.

 
Hi All
I made what I calculated to be an 11 mM stock solution of L-Trp (0.035 gr L-Trp dissolved in 15 ml of 100 mM KH2P04 pH 6.5. 
I checked the abs of this, (10 ul of what I thought was an 11 mM stock solution added to 990 ul of my buffer in a 1 cm cuvette) and the abs at 278 nm  was 1.2, using Ext. Coeff. of 5,579 M-1cm-1,  I calculate the solution I made as being 22 mM.  This is a fairly significant difference, and thinking something was wrong the first I did this I made a fresh stock solution of Trp and got the same results.

Does anyone have any idea what is going on?  Am I using the correct Ex. Coeff?

Arvind Singh Pundir
Arvind Singh Pundir's picture
please check the link and

please check the link and take help of calculator to check your calculation hope it helps as i think your molarity calculation are  true
www.graphpad.com/quickcalcs/molarityform.cfm
 
 
 
 
 

Deadman
Deadman's picture
Here is the most relevant

Here is the most relevant website on this topic.
http://www.molaritycalculator.com

Adams
Adams's picture
There are several molarity

There are several molarity calculators on internet.

Selleck Molarity Calculator

Torics Morality Calculator

to name a few easily copied from google :D