Hi friend 

   I don't know the preparation of 50 mM ethanolamin. But i know 10mM NaCl. First you will calculate 1M = Molecular weight of NaCl per 1000 X Required volume (100 or 200). then you will multiple this answer / 1000 this the ans of 1mM. So you can prepare your buffer. That mean you need 10mM ok. first calculate 10x MW (Molecular weight) of NaCl/1000 x Required volume (100 or 300ml)= Ans/1000. For example (100ml), you will  take 50 ml distilled water and add ans amount of NaCl and dissolved completly then make 100 ml with distilled water. After that you will check pH. that all.

Hi, you can use this website for calculation. http://www.graphpad.com/quickcalcs/Molarityform.cfm

If you have any other problems, please ask.

There are two ways to go about making a 50 mM ethanolamine solution at pH 9.3.

One way is to adjust the pH of an ethanolamine base solution downwards with HCl, using a pH meter to monitor the pH while adding concentrated HCl dropwise to a rapidly stirred solution. Start with a slightly lower volume of water than would be needed to make the solution 50 mM in ethanolamine so there is room for the HCl. Then when the pH is correct, add just enough additional water to bring the ethanolamine to 50 mM.

[Note: pure liquid ethanolamine is 16.57 M. For 1 liter of 50 mM ethanolamine, you need 3.02 ml of the liquid.]

The other way is to mix together a 50 mM ethanolamine base solution with a 50 mM ethanolamine-HCl solution in whatever proportion is needed to get to pH 9.3, using continuous pH monitoring as described above, In this case, the volume doesn't matter; the ethanolamine concentration will always be 50 mM.

As for the NaCl, it won't affect the pH, so you can just add it into the other solutions at 10 mM when you make them.

Here is another approach that I prefer:

I find it convenient to prepare concentrated stock solutions, and mix them together as needed. For example, I might make a 500 mM ethanolamine pH 9.3 solution, filter sterilize it, and keep it in the refrigerator. Then, when I need a 50 mM solution, I can just make a 1:10 dilution of this stock with water. (Warning: the pH of some buffers can shift when they are diluted. You should check this for your buffer.) For NaCl, I would also make a concentrated stock solution. Then you can mix the stock solutions together with water to make whatever composition you need.

Example: 1 liter of 50 mM ethanolamine-HCl (pH 9.3) + 10 mM NaCl

• 100 ml of 0.5 M ethanolamine-HCl (pH 9.3)
• 10 ml of 1 M NaCl
• 890 ml of distilled water

dear mai, 

i agree with Adam sir, for your convenience, first you need to make stock solution of all ingredients then mix them one by one according to your requirement, stir that and add drop by drop HCl. finally make up volume.    

Thank you so much for your kind help..

HI i how to prepare 0.5 M ethanolamine buffer (pH 9.2)?