Sorry guys,  just as in the old days when milk came with cream on the top,
the cream was NOT a colloid when it was separated like that.  The
'colloidal' WHOLE milk that we drink today consists of a suspension of
micro-droplets of cream dispersed in a continuous, aqueous protein sol
(i.e., the milk!).  the cream on top was never a colloid until it was
dispersed - somewhat permanently.  In order to be a colliid, you must first
be dispersed in a continuous phase.  Dry Jello is NOT a colloid until it is
dissolved in hot water, and unless you do something really wrong, the
dispersion persists until the gel forms.  Add back some heat and the gel
becomes a sol, again a colloidal dispersion.

I think I have that essentially right.

Fred

> ----------
> From: 	Vinnie Della Speranza
> Sent: 	Tuesday, September 10, 2002 2:08 PM
> To: 	HornHV@archildrens.org; gcallis@montana.edu;
> histonet@pathology.swmed.edu
> Subject: 	Re: Interesting point! formalin separation from tissues for
> disposal
> 
> Gayle,
> You and I are in agreement. I, like you.consider the lipid in the formalin
> to be a colloid for lack of any better term.it is commonly found floating
> on the surface of the waste formalin. this is where I'm at now. the Safety
> people want it (lipid) out but can't offer any advice on how to do just
> that and of course, I will consider any method that creates additional
> safety concerns for staff and another full time job to accomplish,
> undesirable.
> re: Carrie's suggestion, neutralization followed by drain disposal would
> not be acceptable at my facility. in fact, this would probably cause me
> greater headaches as I would have to prove that no formaldehyde remained
> in the waste before disposal could occur.
>  
> I'm hoping someone will have a reasonable suggestion for what has quickly
> becoming a crisis as they are not allowing me to do any additional
> disposal of tissues or waste formalin until a solution is found. we don't
> have the space to permit this stuff to accumulate.
>  
> Vinnie
> 
> >>> Gayle Callis  09/10/02 11:59AM >>>
> Vinnie, 
> 
> Hazel brings up a good point.  Next question, is what do you do with the
> separate blood and lipid waste? Has your safety people thought of that?
> or
> do you have a way to dispose of these in another manner?  
> 
> Maybe looking into formalin recycling would be a good choice, since you
> have to do so much work to satisfy the safety people.  Then the only waste
> you have to dispose of is what is left in bottom of recycling unit, small
> by comparison to volumes of formalin.  Personally, I don't think one can
> separate lipid out totally, it makes a colloidal solution (hope I am
> thinking correctly here) and I am sure everyone has seen cloudy formalin
> from very fatty tissue - and if you can't get it all out, what does your
> safety people make you do then?? 
> 
> Good luck
> 
> 
> At 09:02 AM 9/10/02 -0500, you wrote:
> >I don't know if I can offer a reasonable solution, but wouldn't these
> >elements be harmless as they are fixed?   I don't understand their
> reasoning
> >for this.   Is the waste company that hauls the spent formalin away
> >suggesting this?    We have to pour ours off as well.
> >I sure hope this isn't something that will come my way.    I'll be
> >interested in replies to this thread.
> >Hazel
> >
> >> -----Original Message-----
> >> From:    Vinnie Della Speranza [SMTP:dellav@musc.edu]
> >> Sent:    Tuesday, September 10, 2002 8:43 AM
> >> To:    histonet@pathology.swmed.edu
> >> Subject:    formalin separation from tissues for disposal
> >> 
> >> I know that this topic has been discussed on the list numerous times
> >> before however we are being faced with a slightly different slant that
> I
> >> would welcome your input on.
> >>  
> >> Our Safety dept. has become conerned that our waste formalin contains
> >> blood and lipid that they feel must be separated from the formalin
> before
> >> it can be carted away. 
> >> We currently use a filtering funnel when pouring off the waste formalin
> >> but this won't extract the lipid and blood which are in liquid
> suspension
> >> in the formalin.
> >>  
> >> Has anyone else been required to address this issue? I'm hoping someone
> >> can offer a reasonable solution that will satisfy our Safety folks.
> >>  
> >> thanks
> >>  
> >>  
> >>  
> >> Vinnie Della Speranza
> >> Manager for Anatomic Pathology Services
> >> Medical University of South Carolina
> >> 165 Ashley Avenue  Suite 309
> >> Charleston, SC 29425
> >> Ph: 843-792-6353
> >> fax: 843-792-8974
> >
> >
> >
> Gayle Callis
> MT,HT,HTL(ASCP)
> Research Histopathology Supervisor
> Veterinary Molecular Biology - Marsh Lab
> Montana State University - Bozeman
> 19th and Lincoln St
> Bozeman MT 59717-3610
> 
> 406 994-6367 (lab with voice mail)
> 406 994-4303 (FAX)
> 
> email: gcallis@montana.edu
> 
> 
> 
>