It should be specified that in the preparative scale oxidations of cellobiose, the total volume of the reaction mixture was 2 mL at a phosphate buffer concentration of 200 mM. The column employed for HPLC-MS analysis was Poroshell 120 EC-C18 (2.7 μm), and samples were filtered through a short plug of Celite prior to analysis to eliminate the copper complexes.
We identified the peak in Figure S19 in the Supporting Information as a leaching product from the HPLC column when H2O2/Et3N is employed as oxidant for cellobiose degradation. Upon further analysis, the peak giving rise to m/z = 118 and 235 is consistent with protonated triethylamine N-oxide [Et3NOH]+ and [(Et3NO)2H]+, respectively.
