Buffers Of Sucktitude.

joshua1

I have to make up an electroporation buffer, one that i cribbed of someone elses lab.


In this buffer i need to make up;

One component is Na2HPO4-7H2O (0.7mM)

I only have Na2HPO4-2H2O and NA2HPO4

Does the -7H2O make it that important? How much Na2HPO4-2H20 would i need to add to make up for not having the -7H20 variety.

I thought i knew what to do, and calculated out molecular weights etc, ending up adding a bit less.

BUT! I saw a formula for PBS that required MORE Na2HPO4-2H2O, if it was used instead of plain Na2HPO4.


This is driving me insane!

So, any chem-masters here?

Rook

joshua1 wrote: »

I have to make up an electroporation buffer, one that i cribbed of someone elses lab.


In this buffer i need to make up;

One component is Na2HPO4-7H2O (0.7mM)

I only have Na2HPO4-2H2O and NA2HPO4

Does the -7H2O make it that important? How much Na2HPO4-2H20 would i need to add to make up for not having the -7H20 variety.

I thought i knew what to do, and calculated out molecular weights etc, ending up adding a bit less.

BUT! I saw a formula for PBS that required MORE Na2HPO4-2H2O, if it was used instead of plain Na2HPO4.


This is driving me insane!

So, any chem-masters here?

The 7H2O is just how much water is crystallised with it. It's not a different molecule so they should be interchangeable. Although they'll obviously have different formula weights. So 1 mole of Na2HPO4-7H2O (containing 1 mole of Na2HPO4) weighs more than 1 mole of Na2HPO4-2H2O (containing 1 mole of Na2HPO4) which weighs more than 1 mole of Na2HPO4.

joshua1

so it weighs more, but contains less of the compound, thus i need to add more?