Is there a way of testing the strength of 10% formalin?

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Hello histonetters,
	At our hospital laboratory the staff have been making up 10% formal saline 
for 40 years. An odd time one would come across a dud bottle of 38-40% 
formaldehyde and discard.
	Recently however there has been a lot of dud bottles and I'm wondering is 
it the unseasonally cold spell of weather. The temperature in the Chemical 
store in the yard may have dropped well below (-7min.) the recommended 
10-25C some nights and I'm wondering would this result in weak formalin.
	There also is an uncharacteristic clear red tinge to blood stained 
specimens  as if it had a higher than usual alcohol content. (We decided 
not to change over to NBF years ago as it works fine for most Immunos. We 
are in the UKNeqas ICC and doing OK.
	I thought even if the temp. dropped below 10C and subsequently was brought 
up to room temperature and diluted to make 10% formal saline then it would 
be fine. Does anyone have any experience of this kind of thing???
	Any thoughts ?? I have asked the supplier for a "certificate of 
conformity" for this batch and the date of manufacture and it is pending.
There is a use by date on it of Oct 2001. Is there a way of testing the 
strength of the formaldehyde or would a low pH indicate a deteriorating 

Annette Ryan
Medical Laboratory Technologist
Histology Laboratory
Our Lady of Lourdes Hospital
Co Louth

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