Re: reagents

<< Previous Message | Next Message >>
From:"R.Wadley" <>
Date:Tue, 10 Aug 1999 11:11:20 +1000
Content-Type:text/plain; charset="us-ascii"

	Dear All,

	Just a quick note about ancient (or more importantly dry) picric acid.

	I've worked in a couple of labs where I've come cross dry, solid picric
acid, once in a large glass jar sealed with a cork!

	First Handle with Extreme Care:  Do not touch or move the container until
you have a bucket of water to place it into.  Then wearing a face shield,
heavy gloves (leather is good), & preferably a leather apron, GENTLY place
the container into a bucket of water.  It is also best to clear onlookers
from the scene, incase you trip over one.

	I prefer to use distilled or deionised water so I can use the picric acid
once its saturated.

	Leave it in the bucket at least 1-2 days before attempting to loosen the
lid.  Again use protective gear.  Then fill with distilled or deioinised
water.  Leave for another day or 2 keeping the water topped up.  The very
gently agitate (by inversion is best) Your picric acid is now ready for use
or disposal.

	I have had the experience where "professional hazardous waste folks" have
refused to touch picric acid until the above steps have been taken.

	Never strike, drop, apply flame to or otherwise apply a kinetic ignition
force to picric acid, it does make a big bang, in a glass jar it is a
potential & potent hand grenade.  Even the attempt to twist off a dry
lid/cork/stopper can be sufficient to set this stuff off.  Once in
university (in the good old days) I left a prac with both hands completely
yellow from picric acid, the only safety advice I got was not to clap my
hands together!  Years later I found out it is a neuro toxin.

	As an aside, picric acid was apparently very popular with the Navy during
WW2 hostilities, it is a powerful propellant that will work when damp,
unlike gun powder!


	Rob W.

At 04:23 PM 8/9/99 -0400, you wrote:
>In general 8 years is not very long on the shelf for many of the dyes 
>you mention as long as they stay dry. I have been known to comb the 
>dustiest of shelves in search of Congo Red lots from the fifties (they 
>have a higer due content than anything you can buy now). Hematoxylin 
>will also last for just about ever. As for testing, chemical and 
>empirical tests for most common dyes are in "Conn's Biological 
>Stains'" If you run across a jar of picric acid that has been around 
>a long time, don't touch it, stop rummaging completely. Get some 
>professional hazardous waste folks to help you out.

R. Wadley, B.App.Sc. M.L.S, Grad.Dip.Sc.MM
Laboratory Manager
Cellular Analysis Facility
School of Microbiology & Immunology
UNSW, New South Wales, Australia, 2052
Ph (BH) 	+61 (2) 9385 3517
Ph (AH)	+61 (2) 9555 1239
Fax 	+61 (2) 9385 1591

<< Previous Message | Next Message >>