An optimized capillary electrophoresis method for the simultaneous analysis of biomass degradation products in ionic liquid containing samples

• Simultaneous separation of carbohydrates in ionic liquid solutions was performed.
• Statistical design of experiments was applied for the method optimization.
• Experimentally formed cellooligomers were separated in ionic liquid samples.

An indirect capillary electrophoresis method for a quantitative determination of mono-, di- and oligosaccharides was developed to investigate biomass degradation, the isomerization of glucose into fructose and conversion of fructose to 5-hydroxymethylfurfural (5-HMF) in ionic liquids (ILs). Three chromophores, namely 2,6-pyridinedicarboxylic acid (PDC), maleic acid and phthalic acid, were used to perform indirect detection. The electroosmotic flow (EOF) was reversed to reduce analysis time, using 1-tetradecyl-3-methylimidazolium chloride (C14MImCl). The simultaneous separation of the underivatized mono-, di- and oligosaccharides was performed using four cellodextrin oligomers (cellotriose, cellotetraose, cellopentaose, cellohexaose), eight carbohydrates (xylose, fructose, glucose, galactose, lactose, cellobiose, raffinose, sucrose), two organic acids (acetic acid, levulinic acid) and 5-HMF. The best performance was obtained using background electrolyte (BGE) composed of 138.2 mM NaOH, 40 mM maleic acid and 5 mM C14MImCl, the applied voltage was −21.7 kV. The linear ranges for analyzed compounds were following: organic acids, raffinose and sucrose from 0.20 to 7 mM, cellodextrin oligomers from 0.25 to 5 mM, other analyzed carbohydrates from 0.25 to 7 mM and 5-HMF from 0.05 to 7 mM. The relative standard deviations (RSD) of peak areas varied from 3.47 to 9.62% during a 5-day analysis period and 0.58–5.29% during one day.