saturated ammonium acetate
Shanthi Adimoolam
Shanthi Adimoolam
Hi,
I am trying to use a procedure from a recent biotechniques journal for
the large scale purification of plasmid DNA. It called for the
preparation of a saturated ammonium acetate solution. I wasn't sure
exactly what they meant by that. ANy suggestions?
Thanks in advance.
-shanthi
Sailesh Surapureddi
Oh! thats easy, try and saturate DH20 with ammonium acetate and you would
find that it requires 3M conc. In other words its 3M Sod.Acetate for
Plasmid DNA purification.
Cheers
Sailesh.
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HIRANYA ROYCHOWDHURY
Sailesh,
That is not quite correct. You can make 10M Ammonium acetate at
room temperature (22-23 C). This solution is extremely viscous if cooled
to 0 C and takes a long time to freeze at -20 C. Sodium acetate at 3M is
also not quite saturated... you can dissolve sodium acetate (the salt) at
least to 5M.
I think the saturated ammonium acetate mentioned in the
Biotechniques could be the 10M one.
>>>>>>>>>>>>>>>>>>>>>>>>>>>
Hiranya S. Roychowdhury
Plant Genetic Engineering Lab.
Box 3GL, NM State Univ.
Las Cruces, NM 88003
Phone: (505) 646-5785
hroy...@nmsu.edu
<<<<<<<<<<<<<<<<<<<<<<<<<<<
Sailesh Surapureddi
>Sailesh,
> That is not quite correct. You can make 10M Ammonium acetate at
>room temperature (22-23 C). This solution is extremely viscous if cooled
>to 0 C and takes a long time to freeze at -20 C. Sodium acetate at 3M is
>also not quite saturated... you can dissolve sodium acetate (the salt) at
>least to 5M.
> I think the saturated ammonium acetate mentioned in the
>Biotechniques could be the 10M one.
>
>
OOps! Did I goof, I suppose not. I tried dissolving 6M once just for the
sake cutting down the vols to half and I never could get it going into
solution. 3M was never a problem and most of the mini prep protocols use 3M
and this was never a problem to get into solution, though this conc itself
takes some amount of time and stirring. Ofcourse the paper in Biotech.
mentioned aforewith may have missed my table.
But thanks for mentioning it, it makes me give it a shot again (But I am
sure I was correct with my earlier try). On the other hand why would
anybody use 10M solution when 3M does the job (if it isnt just for
speculation sake?).It doesnt make sense to me. Pls. correct me if I am
wrong again.
HIRANYA ROYCHOWDHURY
Hello Sailesh,
I was not talking about 6M Na-acetate or 6 M K-acetate. The 10M
Ammonium acetate solution is required in some manipulations. However, I
have been able to dissolve k-acetate to 5M with a slight warming and it
usually stays in solution at room temp. if the ambient temp does not drop
below 22 C (which is a possibility during the night). Upon storage for a
long time crystals do form in a 5M solution which goes back to solution
upon rewarming to about 28-30 C.
In some cases one needs to use acetate salts at a higher conc.
(2M) to ppt small NAs and also to rid DNA solution of protein; in such
cases one can use 3M solutions but the final volume will be 3x,
and hence the use of the 10M solution.
with regards,
Hiranya
>>>>>>>>>>>>>>>>>>>>>>>>>>>
nsau...@molbiol.ox.ac.uk
Never mind all this talk about 3M, 6M, 10M or whatever; I've always been under
the impression from basic chemistry that "saturated" means "dissolved until no
more will dissolve".
Neil Saunders
Sailesh Surapureddi
Hello Hiranya:
Sir, Pls refer to your y'day's comments in quotes "You can
make 10M Ammonium acetate at room temperature (22-23 C)". I dont mean any
disrespect but today you say
" However, I >>have been able to dissolve k-acetate to 5M with a slight
warming and it usually stays in solution at room temp".
Pls underline slight warming and in Dict. sense, Saturation means
just going into the solution upto the brim and not warming, if warmed then
it becomes Supersaturation.
I am just in Sweden and even here the room temps never go below
16C, but I was unable to make the higher conc of Sod. acetate go into
solution. On the other hand, I never had problem for K-acteate even at 5M
conc and our room temps (infact its sitting right now cooly). Anyway I
guess we wouldnt be going any further with this topic as you said yourself
'all you need is 3X as the final conc' for most of the DNA manipulations,
so I guess if one suggests 3M solution for routine work (one has to make
manipulations in protocols in specific circumstances ofcourse), there is no
harm. I guess you would agree with me in this.
Best regards and hope to meet you in further discussions
Claudia Strehl
I´m not sure about the concentration of a saturated NH4Ac-solution but
maybe the definition for a saturated solution will help you:
you have to solve as much salt as possible in the solvens (water).
The solution is saturated when you can you can observe salt that is not
solved
cheers
Claudia
Claudia Strehl
Claudia Strehl
tuantr...@gmail.com
I've been making saturated solution of this salt and I'm quite sure that at room temperature, even the concentration of 10M is not saturated.