The free fermentable sugars (glucose, cellobiose,
and xylose), several known inhibitors (formic acid, acetic
acid, levulinic acid, furfural, 5-hydroxymethylfurfural (HMF)) and
ethanol were directly quantified using a HPLC system (1200 series,
Agilent) equipped with a Bio-Rad Aminex HPX-87H column
(300 7.8 mm).