Re: Buffer Protection (How about heat?)

From:Abizar Lakdawalla <>

It is more usual to store buffers in a concentrated form. Two advantages,
storage takes less volume, and the high salt concentrations prevent growth.
In our labs, we prepare most buffers at 10 or 20x, autoclave, cool, add
filtered detergent (Tween-20, etc.  mixed with equal volumes of sterile water
to make pipetting, filtering  much more easier) and store at room temperature.
We dilute enough to last us a couple of days.
Sodium azide is the most common preservative we use in buffers that contain

"J. A. Kiernan" wrote:

>   Refrigeration and thymol are harmless and will slow down microbial
>   growth, but isn't the preservation of a microwave retrieval
>   solution built in with its use, especially in a laboratory that
>   does immunohistochemistry every day?  If slides are heated in the
>   liquid to near boiling for several minutes every day, and the
>   container has a cover over it while it's in use, cooling down,
>   doing nothing or warming up, few bacteria and fungal spores should
>   fall into it, and most of those that do get in will be executed
>   en masse, every day, when the solution is used again.
>   This is a circumstance in which it is not only more economical but
>   also more microbiologically hygienic to use a solution repeatedly
>   than to throw it out every day. Obviously you can't go on for
>   ever, because there will be evaporative losses (easily corrected),
>   bits of sections in the retrieval solution (easily removed by
>   filtering) and eventually some sort of grunge derived from any
>   accumulated boiled bacterial corpses and bits of hyphae that are
>   small enough to pass through filter paper. There's no obvious way
>   to define an end-point for the last item. If the solution is
>   transparent to the eye, it's unlikely to deposit crud on the
>   sections, but it is conceivable that residual dead bacteria might
>   cause false-positive results in immunohistochemical searches for
>   bacterial antigens. Is this really a potential problem, or is it
>   just a theoretical one?
> ---------------------------------------------------
> On Mon, 16 Oct 2000, Amos Brooks wrote:
> > I'd try to free up some refrigerator space to keep the buffer in at
> > least. You could also try some thymol to prevent fungi, I don't think
> > that would interfere with the buffer, would it??
> > free space haha what's that .....  > Amos Brooks
> > Luis Chiriboga wrote:
> > > I usually make large quantities of microwave solution on the order of
> > > 20L (I use a lot and I'm lazy). Has anyone ever added a preservative to
> > > their buffer?  I occasionally get some growth (nothing bigger than an
> > > occasional tadpole) in the carboy.
> ---------------------------------------------------
>  John A. Kiernan,
>  Department of Anatomy & Cell Biology,
>  The University of Western Ontario,
>  LONDON,  Canada  N6A 5C1

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