The easiest way of making this buffer is: as follows:
1.Make a 0.1M solution of 2-(N-morpholino)ethanesulfonic acid ( note this is the acid form (it is protonated) ( best to start with the MES monohydrate as the water content is defined ). There no need to measure the pH of this solution. This is solution A.
2. Make a separate 0.1M solution of 2-(N-morpholino)ethanesulfonic sodium salt ( note this is the NOT the acid form (it is not protonated; sodium is the counter ion). There no need to measure the pH of this solution. This is solution B.
3. calibrate your pH meter accurately with calibration buffers.
4. Put some of solution A in a beaker, enough to ensure that the pH meter electrode is fully covered .
5. Slowly add solution B while stirring the mixed solution. Read the pH continuously. The pH will change as you add solution B.
If you overshoot the pH just add some of solution A . the concentration of MES is always 0.1M.
When the pH has reached pH6.1 you will have a buffer solution which is described accurately as 0.1M-2-(N-morpholino)ethanesulfonic acid sodium salt buffer pH6.1 (The concentration refers to the concentration of the buffer ion (MES)).
The volume of the solution is not defined . The buffer is defined by the pH and the concentration of the MES.
For a different concentration of MES make up solutions A and B with the concentration you require. The rest of the protocol is the same.
The recommended range for this buffer is pH5.5 to 6.7 ( ref. to Fluka catalogue)
The pH of this buffer may be temperature sensitive. If you use it at a different temperature from that at which it was made it may have a different pH. Data on this temperature coefficient can probably be obtained from Fluka. Please note that the temperature compensation on your pH meter will only compensate for the electrode. It will not compensate for the change in pH of the buffer itself.
The easiest way of making this buffer is: as follows:
1.Make a 0.1M solution of 2-(N-morpholino)ethanesulfonic acid ( note this is the acid form (it is protonated) ( best to start with the MES monohydrate as the water content is defined ). There no need to measure the pH of this solution. This is solution A.
2. Make a separate 0.1M solution of 2-(N-morpholino)ethanesulfonic sodium salt ( note this is the NOT the acid form (it is not protonated; sodium is the counter ion). There no need to measure the pH of this solution. This is solution B.
3. calibrate your pH meter accurately with calibration buffers.
4. Put some of solution A in a beaker, enough to ensure that the pH meter electrode is fully covered .
5. Slowly add solution B while stirring the mixed solution. Read the pH continuously. The pH will change as you add solution B.
If you overshoot the pH just add some of solution A . the concentration of MES is always 0.1M.
When the pH has reached pH6.1 you will have a buffer solution which is described accurately as 0.1M-2-(N-morpholino)ethanesulfonic acid sodium salt buffer pH6.1 (The concentration refers to the concentration of the buffer ion (MES)).
The volume of the solution is not defined . The buffer is defined by the pH and the concentration of the MES.
For a different concentration of MES make up solutions A and B with the concentration you require. The rest of the protocol is the same.
The recommended range for this buffer is pH5.5 to 6.7 ( ref. to Fluka catalogue)
The pH of this buffer may be temperature sensitive. If you use it at a different temperature from that at which it was made it may have a different pH. Data on this temperature coefficient can probably be obtained from Fluka. Please note that the temperature compensation on your pH meter will only compensate for the electrode. It will not compensate for the change in pH of the buffer itself.
Thank you kumar, if we haven't thoses (complicated) solutions, can we use another pH specific buffer for Nps functionalization ?
Thank you Tekade. At last I found one scholar describing the buffer preparation correctly for both pH and molarity. Most of the buffer calculators on the internet are incorrect with respect to molarity. They do not fall in line with Henderson-Hasselbalch's calculations.
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