Neutral buffered formalin is best fixative in histopathology. But if by any chance it gets yellowish so what all shall we do to get rid of this problem in laboratories?
The neutral buffered formalin (NBF) must have polymerized. Have you prepared 10% NBF in-house?
If yes, then please note that 10% neutral buffered formalin is a solution of 10% formaldehyde in sodium phosphate buffer containing up to 1.5% methanol.
Methyl alcohol acts as an inhibitor of formaldehyde and prevents polymerization. Therefore, a small amount of stabilizer like methanol is usually added to suppress oxidation and polymerization.
Usually, commercial-grade NB formalin solutions contain methanol as an additive in order to prevent formaldehyde polymerization over time.