Fig. 6

a GC–MS total ion chromatogram (TIC) and mass spectra (insets) of the trimethylsilyl (TMS) and trimethylsilyl-oxime (TMS-oxime) derivatives for compounds of CMC hydrolysis at 45 °C and pH 5.4 using a cel12B, cel8C and β-glucosidase cocktail b predicted fragmentation pattern showing the prominent mass ions of O-pentakis-TMS, (1), and oxime-hexakis-O-TMS, (2) and (3), derivatives of glucose relative to what was reported by Peterson [104] and Kennedy and Robertson [105], respectively. As shown in the elution profile, glucose (G) existing in two different configurations corresponds to that of the open-chain (oxime-hexakis-O-TMS), G1 and G2, and cyclic-pyranose (O-pentakis-TMS), G3 and G4. On the other hand, corresponding peaks for cellobiose are C1 and C2 which exist as the main product of CMC hydrolysis along with that of glucose. The two peaks of different retention time and similar fragmentation patterns detected for each of glucose and cellobiose derivatives represent the alpha- and beta-stereoisomers, in the case of TMS-glucose and cellobiose derivatives, and syn- and anti-oxime isomers in the case of TMS-oxime glucose derivative. The absence of those glucose and cellobiose peaks in GC-blank profile, figure not shown, confirms the current investigation. Other peaks such as CA and INSD were found to belong to citric acid buffer and salicin internal standard, respectively, according to mass spectrometric analysis