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Topic: Help with buffer and preparation of solutions  (Read 843 times)

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Offline EveRod

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Help with buffer and preparation of solutions
« on: June 13, 2021, 12:06:05 PM »
Hello,

I need help with a calculation on buffer preparation, maybe can you help me with it? I would appreciate it

“You need to prepare 50mM Tris Glycine.
Used 5x dilution of 250 mM Tris 1.92 uM glycine buffer BioRad 161-0734, lot 64147898."

The product indicates that the Tris / Glycine is at 10X.
I have doubts about how to proceed. The product also indicates that if we take it to 1X, we must make 100ml buffer and complete with H2O to obtain 25mM Tris, 192mM Glycine.

However, the problem says 5x dilution of 250 mM Tris 1.92 uM glycine.
I wanted to use the formula C1V1 = C2V2, and C1 = 250mM; C2 = 50mM; V2 = 2ml (let's say I want only 2ml); V1 = is what I am looking for.
I got that I had to add for 2ml:
V2 = 2ml
C1 = 250mM
C2 = 50mM
So V1 = 400ul (Buffer) ; add = 1600 ul water

However, I am not sure about this. First, the stock solution in the bottle is at 10X. And then the problem says that you want 5X of that solution. So the concentration to prepare is 50mM.
How should I proceed? I am confused. By the way, the bottle already has the Tris/glycine buffer. In other words, I don't think I should calculate amounts of glycine. Also, I don't understand why the statement says 1.92uM Glycine, and the value on the bottle indicates 192mM. Is it necessary to take these glycin values into account if the original buffer already contains them?
(*This buffer is used for histological experiences)
Thank you in advance for your help,
EveRod

Offline Babcock_Hall

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Re: Help with buffer and preparation of solutions
« Reply #1 on: June 14, 2021, 07:40:18 AM »
Could 1.92 µM glycine be a typographical error?

Offline EveRod

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Re: Help with buffer and preparation of solutions
« Reply #2 on: June 14, 2021, 08:48:08 AM »
Hello,

Thank you for your reply. Indeed, I have just realized that it would be a typographical error. It would be 1.920 M (and not 1.92uM). Because it multiplies the quantities X10: 25mM x 10 is 250mM, 192mM x10 is 1920 mM which corresponds to 1.92M (so I think there is an error, it is not 1.92uM but 1.92M).

However, regarding the main question, Is my calculation correct according to what is asked?

How much buffer and how much water do I have to put into getting 50mM?

In my post, I applied the formula. But when I converted with X (10X, 5X…), I did not obtain the same thing as the equation. Definitely, there is something that needs to be checked.

Also, the information on glycine concentration is necessary, knowing that the product already contains both elements (Tris / Glycine)?

Maybe you or other members in the forum have some ideas to solve this?
Thank you!

Offline Babcock_Hall

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Re: Help with buffer and preparation of solutions
« Reply #3 on: June 14, 2021, 12:31:35 PM »
I do not see any errors in your calculation.  I would bear in mind that the designation of "10x" presupposes a desired final concentration.  If your desired final concentration is different, then all bets are off, so to speak.

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