Maleic acid buffer: Help me make it

Rosanne Casu rosanne at
Sun Feb 18 22:46:52 EST 1996

kernan at (Rich Kernan) wrote:
>In article <scj-1502960907510001 at>,
>scj at (Scott C. Johnson) wrote:
>(message deleted)
>>That there were problems making up a 10x stock of buffer 1 i.e. 1M maleic acid, 1.5M NaCl, pH 7.5.


We routinely make up a 10x stock of this buffer. This is our recipe:

To make 1 litre:

Maleic acid: 116.1g
NaCl: 87.66g
Water to about 800ml

At this point the maleic acid is completely insoluble. Start adding NaOH pellets while stirring the solution. Have patience, the ppt will not solubilize until the pH reaches about 5.5 to 6.0. At this point, start adding the pellets VERY carefully as it is easy for the pH to overshoot. When the pH reaches 7.5, top up with water to the correct volume and then autoclave if desired. This works every time.

Good Luck,

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