Making 25 mM Tris-phosphate Buffer (pH 7.8)

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In summary, the conversation discusses the creation of a new buffer using 25 mM Tris-base and 25 mM phosphoric acid to achieve a pH of 7.8. The purpose and effectiveness of this buffer is questioned, as well as the potential interaction between Tris and phosphoric acid. The conversation also mentions using the buffer in gel electrophoresis.
  • #1
sotellme
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how can i make this buffer? i know how to make Tris- HCl buffer, but how about this one? what is the acid and base here?

25 mM Tris-phosphate (pH 7.8)

any ideas?

thanks.
 
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  • #2
25 mM Tris-base
25 mM Phosphate or phosphoric acid

Adjust the pH to 7.8 with the phosphoric acid
 
  • #3
i thought this method is used for only conjugate pairs. Tris-base
and phosphoric acid are not conjugate of each other, are they?

thanks.
 
  • #4
This is a new buffer to me (I've heard of both tris and phosphate buffers and use them regularly, but never heard of combining the two). What are you using it for (or what is it claimed to be used for)? How well does it buffer? What's the advantage of using this over just a tris buffer or phosphate buffer?
 
  • #5
sotellme said:
i thought this method is used for only conjugate pairs. Tris-base
and phosphoric acid are not conjugate of each other, are they?

thanks.
I don't know, I am not a biochemist. It is how most people go about it.


Moonbear,

Tris-Phosphate when EDTA is added can be used in gel electrophoresis.
 
  • #6
i just don't know how can 25 mM Tris-base added to 25 mM phosphoric acid and still we get 25mM buffer. won't the concentration of each of the solutions change? :eek:
 
  • #7
sotellme said:
i just don't know how can 25 mM Tris-base added to 25 mM phosphoric acid and still we get 25mM buffer. won't the concentration of each of the solutions change? :eek:

I'm not sure how Tris and Phosphoric acid interact, but they must in some way or it wouldn't be a good buffer. So, in general, if you add 25 mM of A and 25 mM of B, you get 25 mM AB. If they don't interact (which wouldn't make sense given the purpose), you'd still have a solution of 25 mM of A and 25 mM of B; in other words, if there was no reaction/interaction between the two, adding B would have no effect on the concentration of A in your solution.
 

FAQ: Making 25 mM Tris-phosphate Buffer (pH 7.8)

1. What is Tris-phosphate buffer?

Tris-phosphate buffer is a commonly used buffer solution in biochemistry and molecular biology experiments. It is made up of two components, Tris (tris(hydroxymethyl)aminomethane) and phosphate, which help maintain a stable pH for reactions and prevent drastic changes in pH due to added acids or bases.

2. Why is a pH of 7.8 important for the buffer?

A pH of 7.8 is considered optimal for many biological applications as it is close to the physiological pH of most living organisms. This pH range allows for optimal enzyme activity and stability, which is crucial for many biochemical reactions.

3. How do I make a 25 mM Tris-phosphate buffer?

To make a 25 mM Tris-phosphate buffer, you will need to mix Tris base and monobasic sodium phosphate in the desired proportions. The exact amounts will depend on the final volume of buffer needed and the concentration of the stock solutions. It is recommended to use a buffer calculator or consult a buffer preparation guide for specific instructions.

4. Can I adjust the pH of the buffer?

Yes, the pH of the buffer can be adjusted by adding either an acid or a base. To increase the pH, add a basic solution such as sodium hydroxide or potassium hydroxide. To decrease the pH, add an acidic solution such as hydrochloric acid or acetic acid. It is important to use a pH meter or indicator to ensure the desired pH is reached.

5. How should I store my Tris-phosphate buffer?

Tris-phosphate buffer should be stored in a tightly sealed container at room temperature. It is recommended to make fresh buffer as needed for each experiment, but if stored properly, it can be used for up to a month. However, it is important to check the pH before using the buffer as it may change over time.

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