M. Vaher et al. / Catalysis Today 196 (2012) 34–41
41
the reaction conditions were optimal for its formation. Increase
in temperature resulted in higher 5-HMF to glucose ratios and at
150 ◦C only a trace amounts of glucose were detected (data not
shown). This is in accordance with the earlier observations that
higher temperature enhances the formation of 5-HMF, whereas
more monosaccharide is produced at lower temperatures [32].
[2] M.E. Himmel, S-Y. Ding, D.K. Johnson, W.S. Adney, M.R. Nimlos, J.W. Brady, T.D.
Foust, Science 315 (2007) 804–807.
[3] N. Mosier, C. Wyman, B. Dale, R. Elander, Y.Y. Lee, M. Holtzapple, M. Ladisch,
Bioresour. Technol. 96 (2005) 673–686.
[4] M.Ø. Petersen, J. Larsen, M.H. Thomsen, Biomass Bioenergy 33 (2009) 834–840.
[5] H. Tadesse, R. Luque, Energy Environ. Sci. 4 (2011) 3913–3929.
[6] H. Zhao, J.E. Holladay, H. Brown, Z.C. Zhang, Science 316 (2007) 1597–1600.
[7] M.E. Zakrzewska, E. Bogel-Lukasik, R. Bogel-Lukasik., Chem. Rev. 111 (2011)
397–417.
[8] H.A. Bardelmeyer, H. Lingeman, C. De Ruiter, W.J.M. Underberg, J. Chromatogr.
A 807 (1998) 3–26.
4. Conclusion
[9] K.R. Anumula, Anal. Biochem. 350 (2006) 1–23.
Capillary electrophoresis was found to be a suitable tool for
the monitoring of hydrothermal pre-treatment and enzymatic
hydrolysis of pre-treated willow. We found an excellent agreement
between the results from CE and HPLC that has been conventionally
used for the monitoring of lignocellulose processing. An advantage
of CE was that it enabled simultaneous separation of different sac-
charides and pre-treatment by-products of lignocellulose, furfural
and 5-hydroxymethylfurfural. CE was also found to be suitable for
the monitoring of cellulose degradation in ionic liquid, 1-butyl-3-
methylimidazolium chloride.
[10] National Renewable Energy Laboratory, Chemical Analysis and Testing Lab-
oratory Analytical Procedures: LAP-002 (1996), LAP-010 (1994) and LAP 017
(1998), NREL, Golden, CO, USA.
[11] Y. Cöpür, D. Kiemle, A. Stipanovic, J. Koskinen, H. Makkonen, Paperi ja Puu
(2003) 158–162.
[12] D.J. Kiemle, A.J. Stipanovic, K.E. Mayo, ACS Symp. Ser. 864 (2004) 122–139.
[13] A. Mittal, G.M. Scott, T.E. Amidon, D.J.1 Kiemle, A.J. Stipanovic, Bioresour. Tech-
nol. 100 (2009) 6398–6406.
[14] S.-J. Shin, N.-S. Cho, Cellulose 15 (2008) 255–260.
[15] H. Zhang, J. Wu, J. Zhang, J. He, Macromolecules 38 (2005) 8272–8277.
[16] V.P. Ananikov, Chem. Rev. 111 (2011) 418–454.
[17] J.S. Moulthrop, R.P. Swatloski, G. Moyna, R.D. Rogers, Chem. Commun. 12 (2005)
1557–1559.
[18] R.C. Remsing, G. Hernandez, R.P. Swatloski, W.W. Massefski, R.D. Rogers, G.
Moyna, J. Phys. Chem. B 112 (2008) 11071–11078.
[19] M. Vaher, M. Koel, J. Kazarjan, M. Kaljurand, Electrophoresis 32 (2011)
1068–1073.
Acknowledgments
This research was supported by the Estonian Science Founda-
tion (Grant No. 7818), EU Commission (FP7, grant agreement no.
229830 IC-UP2 and FP7/2007-2013, grant agreement no. 213139)
and COST Action CM0903. Henning Jørgensen and Pernille Anasta-
sia Skovgaard from the University of Copenhagen (Denmark) are
acknowledged for the compositional analysis of the willow raw
material.
[20] S. Rovio, J. Yli-Kaukaluoma, H. Sirén, Electrophoresis 28 (2007) 3129–3135.
[21] S. Honda, J. Chromatogr. A 720 (1996) 337–351.
[22] S. Rovio, H. Simolin, K. Koljonen, H. Sirén, J. Chromatogr. A 1185 (2008) 139–144.
[23] A.-L. Dupont, C. Egasse, A. Morin, F. Vasseur, Carbohydr. Polym. 68 (2007) 1–16.
[24] Y. Zhen, Z. Pan, R. Zhang, Int. J. Agric. Biol. Eng. 2 (2009) 51–68.
[25] J.R.M. Almeida, T. Modig, A. Petersson, B. Hahn-Hagerdal, G. Lidén, M.F. Growa-
Grauslund., J. Chem. Technol. Biotechnol. 82 (2007) 340–349.
[26] B. Qi, J. Luo, X. Chen, X. Hang, Y. Wan, Bioresour. Technol. 102 (2011) 7111–7118.
[27] Z. Chen, X. Yan, J. Agric. Food Chem. 57 (2009) 8742–8747.
[28] P.C. Meier, R.E. Züd, Statistical Methods in Analytical Chemistry, 2nd ed., Wiley-
VCH Verlag GmbH, 2000, p. 105.
[29] H. Watanabe, Carbohydr. Polym. 80 (2010) 1168–1171.
[30] H. Olivier-Bourbigou, L. Magna, D. Morvan, Appl. Catal. A 373 (2010) 1–56.
[31] A. Varnai, M. Siika-Aho, L. Viikari, Enzyme Microb. Technol. 46 (2010) 185–193.
[32] S. Hu, Z. Zhang, Y. Zhou, J. Song, H. Fan, B. Han, Green Chem. 11 (2009)
873–877.
References
[1] A.J. Ragauskas, C.K. Williams, B.H. Davidson, G. Britovsek, J. Cairney, C.A. Eckert,
W.J. Frederick Jr., J.P. Hallett, D.J. Leak, C.L. Liotta, J.R. Mielenz, R. Murphy, R.
Templer, T. Tschaplinski, Science 311 (2006) 484–489.