The field desorption mass spectra of some oligosaccharides and their permethylates and peracetylates

Field desorption mass spectra have been obtained for a number of di‐, tri‐ and tetrasaccharides, and for some permethyl and peracetyl derivatives. The free sugars usually show intense [M + 1]+ ions thus enabling the determination of molecular weights. The effect of variation of emitter current on the relative intensities of fragment ions has been investigated. Permethylated oligosaccharides show intense molecular ions; in contrast peracetylated oligosaccharides show only weak molecular ions but strong [M  60]+ ions. Information from electron‐impact and field desorption mass spectra is essentially complementary.