FIGURE 6.

ES-MSⁿ analyses of reduced and permethylated derivatives of the largest glycan released by aq. HF. A, the sample recovered from NMR and reduced with NaBD₄ was permethylated and analyzed by positive ion ES-MS on an Orbitrap instrument. The [M+2Na]²⁺ ion at m/z 1275.6 was isolated and subjected to CID giving rise to the product ion (MS²) spectrum shown. B, the [M+2Na]²⁺ ion at m/z 992.5 from A was isolated and subjected to CID giving rise to the product ion (MS³) spectrum shown. C, the [M+2Na]²⁺ ion at m/z 905.4 from B was isolated and subjected to CID giving rise to the product ion (MS⁴) spectrum shown. D, the proposed fragmentation pathways corresponding to the ions observed in A–C. Unless otherwise noted, z = 2 ions are [M+2Na]²⁺ and z = 1 ions are [M+Na]⁺. The symbols are as defined in the legend to Fig. 4.