In our experience n-propyl gallate added to mounting media reduces fading of fluorescence from many different fluorophores during fluorescence microscopy. The following is a simple recipe for making an anti-fade mounting medium containing n-propyl gallate.

•  Prepare a 10X PBS stock solution.
•  Prepare a stock solution of 20%(w/v) n-propyl gallate (Sigma P3130) in dimethyl formamide or    dimethyl sulfoxide. (Note: n-propyl gallate does not dissolve well in water-based solutions.)
• Thoroughly mix 1 part of 10X PBS with 9 parts of glycerol (ACS grade 99-100% purity) and    slowly add 0.1 part 20% n-propyl gallate dropwise with rapid stirring.