[Histonet] Re: Ethanol denatured with toluene

[Bob Richmond]

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