Endo F3 modification to the workflow. (A) Representative spectrum for a serum standard with annotations for a set of putative N-glycan structures containing a fucose on the first core N-acetylglucosamine. The top half of the spectrum is PNGase F treated only. The bottom half of the spectrum is Endo F3 and PNGase F treated. (B−D) N-glycan profiles of a serum standard and a plasma standard were analyzed by MALDI-FTICR MS in quadruplicate by a treatment with PNGase F or a PNGase F and Endo F3 mix. The intensities of a noncore fucosylated N-glycan (m/z 2289.7326), core-fucosylated N-glycan (m/z 1809.6393), and Endo F3 product (m/z 1460.5020), respectively, are displayed for both treatments. The N-glycan compositions are represented by blue squares for N-acetylglucosamine, green circles for mannose, yellow circles for galactose, purple diamonds for sialic acid, and red triangles for fucose.