An
AMINEX HPX-87P carbohydrate analysis column (BioRad,
Hercules, CA) operating at 85 C with ultrapure
water as a mobile-phase (0.6 mL/min) was used. Furfural
and hydroxymethylfurfural (HMF) content was analyzed
by HPLC in a 1100 HP liquid chromatograph, equipped
with a 1040 A UV-diode-array detector; the separation
was performed with a Bio-Rad HPX-87 H column, operating
at 65 C with 89% H2SO4 (5 mM) and 11% acetonitrile
as an eluent at a flow rate of 0.7 mL/min. Acetic and formic
acids analysis was carried out with the HPLC system
with a refractive index detector mentioned above with a
Bio-Rad HPX-87 H column at 65 C temperature. The
mobile phase was 5 mM H2SO4, at a flow rate of 0.6 mL/
min. Glucose concentration from enzymatic hydrolysis
samples was measured by an enzymatic determination glucose
assay kit (Sigma GAHK-20). Ethanol was measured
by gas chromatography, using a HP 5890 Series II apparatus
equipped with an Agilent 6890 series injector, a flame
ionization detector and a column of Carbowax 20 M at
85 C. The injector and detector temperature was maintained
at 150 C. All analytical determinations were performed
in duplicate and average results are shown.
3.