Determining levels of ammonium sulfate and magnesium sulfate

Frank Fuerst ffrank at rz.uni-potsdam.de
Tue Mar 20 06:32:40 EST 2001


dsummers at mtcnet.net (Dana Summers) wrote:

>6. Saturate to 0.7 saturation. How many grams of ammonium sulfate do
>   I add to 1 liter of solution?

442g at 0°C, 470 at room temperature, data taken from a protein
methods lab book - I think it's called "Labfax"

>7. Dissolve the precipitate from 0.7 saturation in 0.25 saturated 
>   ammonium sulfate. How many grams of ammonium sulfate do I add to
>   make a 0.25 saturated ammonium sulfate if I have 10 grams of precipt?

I usually neglect the ammonium sulfate in the pellet, just cleanly
discard the supernatant and add 0.25 saturated solution (144g/l at RT)

>8. Adjust pH to 5.0.
>9. Let stand 2 days at 25 degrees C.
>10. Filter.
>11. Recrystallize the crystals on the filter pad in 0.25 saturated 
>    ammonium sulfate at pH 5.0 about 8 times. How many grams of
>    ammonium sulfate do I add to make a 0.25 saturated ammonium
>sulfate     if I have 10 grams of crystals?

Here clearly you can neglect AS in the crystal suspension, just work
with 25% AS in the solvent.

I don't have tables for MgSO4, sorry.

Bye, Frank




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