[Histonet] Re: Ethanol denatured with toluene

[Edwards, Richard E.]

We  used to  use  toluene on our tissue  processor, it  replaced benzene, ah  the  good  old  days!!

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu [mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Bob Richmond
Sent: 06 March 2013 15:25
To: histonet <@t> lists.utsouthwestern.edu
Subject: [Histonet] Re: Ethanol denatured with toluene

Jackie O'Connor writes: >>I am currently in Germany running a QC inspection of a histology division. The histo lab uses ethanol denatured with toluene - I have never come across this before. I have been trying to troubleshoot their H+E stain, and I've been stumped for a long time as to why the sharpness and crispness I'm looking for isn't quite right. Could the toluene in the ethanol used to make dilutions be the culprit? I've not been able to find any references to toluene use in US products. Any input would be greatly appreciated.<<

I've never encountered denaturation with toluene before, and I'm not sure it's a BATF-approved denaturant in the US. The German Wikipedia http://de.wikipedia.org/wiki/Verg%C3%A4llung
makes reference to denaturation with toluene ("Toluol" in German).

I think toluene is a poor choice for a denaturant, because of its toxicity (similar to xylene and benzene), and because it may dissolve some dyes out of tissue sections. The German Wikipedia article doesn't mention anything like our reagent alcohol (90% ethanol, 5% methanol, 5% isopropanol).

I'd find out what other histology labs in Germany use. Wikipedia lists a number of possibilities - I'm going to leave this in German, since your client will need to look at it anyway:

>>Für die Verwendung als Rohstoff in der chemischen Industrie sind 
>>gängige Vergällungsmittel Methylethylketon, Petrolether, Toluol und 
>>Cyclohexan. Weitere zugelassene Stoffe sind Schellack, 
>>Fichtenkolophonium, Phthalsäurediethylester, Thymol, Diethylether und 
>>tert-Butanol in Verbindung mit Isopropanol oder Denatoniumbenzoat.<<

Bob Richmond
Samurai Pathologist
Maryville, Tennessee USA

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