What's chromic-sulfuric acid?

Wolfgang Schechinger Wolfgang.Schechinger at med.uni-tuebingen.de
Mon Mar 27 12:00:40 EST 2000


John,

the main problem with chromosulfuric acid is its chromium content 
wich makes it difficult to get rid of since it needs to be treated as 
toxic waste (at least in Germany). Chromium (V) is carcinogenic and a toxic heavy metal.

>From the chemical point of view, it is a *very* strong oxidant that 
will eat up nearly everything. It is *really* dangerous stuff, thus
weare gloves, a coat and goggles. When you immerse wet stuff, 
chromosulfuric acid will become hot and may squirt (it behaves like 
conc. sulfuric acid). Combustible material might start to burn when 
it gets in contact with the mixture.

If the acid in your container is still ok (orange colored - it will 
go green when it's used up (reduction of Cr (V) to Cr (III)) you 
also might want to use it for cleaning glassware that is resistant 
to other special mixtures (like KOH + isopropanol) instead of simply 
discharging it. Make sure that the water you use for flushing brings 
as little chromium as possible into the sink, using an "intermediate" 
flushing container (containing some water) instead. 

If your problem is decontamination from DNA, better use dilute 
hypochlorit (5 to 10 %), commercial bleach will do the job. 

All the best, 

Wolfgang

PS an anecdote: When I was using the stuff (some 10 liters in a big 
glass aquarium) for cleaning my glassware in the metallo-organic 
chemistry course, I remember there was a torn up glove reaching til 
the elbow we used for diving after our flasks. And when this glove 
was wet (it was flushed with water afterwards), one's fingers became 
hot and I always wondered if this heat came from the reaction of 
chromosulfuric acid with the water or with my fingers...

----

> From:          John Dixon <jpcd100 at mole.bio.cam.ac.uk>
> Subject:       What's chromic-sulfuric acid?
> Date:          Mon, 27 Mar 2000 16:35:08 +0100
> Organization:  University of Cambridge, England
> Reply-to:      jpcd100 at mole.bio.cam.ac.uk
> To:            methods at hgmp.mrc.ac.uk

> 
> > 
> > -The shafts of Gilson Pipetteman are resistant to just about
> > ANYthing. -They appear to be made of something akin to teflon, are
> > autoclavable and -nearly indestructable. -I occassionally go as
> > far as to soak a DRY shaft in chromic-sulfuric acid -(chromerge)
> > for several hours. One MUST rinse in H2O VERY well afterward.
> > 
> > The use of chromic-sulfuric acid is frowned upon, it is on the
> > list of chemicals you should definedly NOT use ! Dangerous stuff !
> > 
> 
> 
> Hi, I have just discovered that a container labelled "ACID" in a
> fume hood we have inherited, in fact contains 3 litres of
> chromic-sulphuric acid. I remembered a mention of it in this thread,
> and wondered if anyone could enlighten me on just how dangerous it
> is, and in what particular ways (other than corrosive, obviously!). 
> 
> I couldn't find any info by searching for chemical safety sites on
> the web so any good links for that would be useful too.
> 
> Thanks
> 
> JD
> 
> -- 
> John Dixon                    Lab 44 (1223) 334131
> Wellcome/CRC Institute        Fax 44 (1223) 334089
> Cambridge University
> United Kingdom CB2 1QR       e-m: jpcd100 at mole.bio.cam.ac.uk
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Dr. Wolfgang Schechinger, Dept. of Pathobiochemistry
University of Tuebingen, Germany
email: wolfgang.schechinger at med.uni-tuebingen.de 
wwWait: http://www.medizin.uni-tuebingen.de/~wgschech/start.htm
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