Re: glutaraldehyde

From: "Gordon J. Holtslander" <holtsg@duke.usask.ca>
Subject: Re: glutaraldehyde
Date: Mon, 15 Mar 2004 23:27:18 -0600

> Its used in microscopy as a tissue fixative. Check microscopy suppliers,
> like pelco for example:

One problem is that those are rather expensive, and come in very
concentrated form. In order to harden a gelatin solution containing
10g of gelatin, 1 to 2 ml of 2.5% solution is the typical range. If
the gelatin solution is low concentration, or the gelatin has low
molecular weight (or low Bloom strength), the solution may take more
GTA before becoming too viscous or irreversibly solidified. Either
way, at this quantity and concentration, the health hazard is a very
well manageable level with ordinary good darkroom
precaution. Additional safety warning is in order if you obtain your
GTA at a much higher concetration.

Another nice thing about glutaraldehyde is that it smells like citrus
scent, and it's not offensive smell. (Warning: don't smell it -- if
you smell it, it means you need ventilation.)

There are several sterilization supply products such as MaxiCide,
which is 2.5% glutaraldehyde solution in acidic pH. These products
contain an anticorrosion agent, typically sodium nitrate. I initially
worried about impurities in these products affecting silver halide
sensitizers, but so far I find the effects are minimal.

> For others considering using glutaraldehyde a good health & safety
> outline:
>
> http://www.ccohs.ca/oshanswers/chemicals/chem_profiles/glutaraldehyde/health_glu.html

This seems more reasonable than the one posted earlier. But the
quantity, concentration, and frequency of use required for hardening
photographic gelatin in our typical batch sizes is much lower than the
typical use for histology or sterilization process. (Poor lab techs
are doing that kind of stuff all day long.)

As a gelatin hardener, glutaraldehyde is an excellent agent. I use
nothing but GTA now. Within alt community, there may be a bit of curve
at the beginning, but I don't see why this won't become a very popular
hardener once supply issue is cleared. I would strongly recommend alt
processors and silver gelatin emulsion hobbists to call YOUR regular
chemical supply sources (such as Photographer's Formulary) and tell
them you want to buy 500ml of 1% or 2.5% glutaraldehyde solution (with
pH adjusted acidic to prevent polimerization) FROM THEM and also tell
them you know other people who want it.

--
Ryuji Suzuki
"All the truth in the world adds up to one big lie." (Bob Dylan 2000)