[Histonet] Hard water

[Matthew Ibbs]

Thanks for the replies to my question regarding minerals in "hard" tap 
water used in the production of formalin.  I'm glad there's no known 
issue with interactions between the minerals and the fixation process. 
That clears up a few points that we've been asked about recently.

René:  Regular testing of air quality around personnel and in general in 
lab areas is required by Polish law, and is carried out by the local 
sanitation and epidemiology laboratory.  Exposure to formaldehyde is 
pretty well controlled but the purchase of ready made NBF is almost 
unheard of - mostly owing to costs. The Polish health service is not 
particularly well off and NBF costs around 10 times more than the raw 
materials needed to make it in house.

Gudrun:  Thanks for your input.  At least in the case of our laboratory, 
formalin is used rapidly, around 50 litres per day.  We buffer our 
formalin and the pH of our water, buffers (pre-mixed) and final formalin 
solution are all 7.  No problems here then.  The smaller labs in our 
area though, may or may not buffer their formalin and some of them do 
very little work and so may be storing formalin for extended periods. 
That being the case, the DNA fragmentation you mentioned would certainly 
interfere with ISH, though possibly less so with immunohistochemistry. 
This nicely lines up with what we've been observing locally.  In house 
IHC and ISH work OK. Material referred to us from outside often works 
with IHC but ISH (usually FISH) results in very weakly fluorescent signals.

Thanks again for the replies.

Matthew.