Another thing with this type of methylation is the resaponification of short chain FAME in time. You can prevent this by neutralizing the NaOH with NaHSO4.H2O. See ISO http://www.iso.org/iso/iso_catalogue/ca ... mber=34610 or http://www.iso.org/iso/iso_catalogue/ca ... mber=43172 or http://www.iso.org/iso/iso_catalogue/ca ... mber=28897

Interesting link: METHYLATION OF FATTY ACIDS – A BEGINNER'S GUIDE