I'm making up some 4% formaldehyde solution from powdered paraformaldehyde. It is brought into solution using NaOH pellets then the pH is brought down with HCl following addition of PBS. However this time while making it I forgot to add the PBS until I'd already added about 12ml 1M HCl. I have two questions about this:
1) Do you think adding the HCl directly to the formaldehyde before PBS may have lead to any direct HCl-Formaldahyde reaction which may lower the efficiency of formaldehyde as a fixative?
2) I've read online that HCl and formaldehyde can react under some conditions to form a potent carcinogen, bis-chloromethyl ether. I assume the conditions are not RT in a normal lab as it wouldn't be on so many protocols, but is anyone aware under what conditions this reaction may occur?
Many thanks for your help,