Rapid Determination of Carbohydrates in Hardwoods by High Performance Anion Exchange Chromatography

The sugars in eucalypt and cottonwood hydrolysates were analysed by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD). Reported conditions for separating softwood hydrolysates were not optimal for hardwoods because of the low mannose levels in hardwood hydrolysates. The long run times of conventional techniques also restrict sample throughput. A faster separation was obtained by introducing a controlled amount of carbonate onto the column. Apart from co-elution of rhamnose and galactose, the sugars in hardwood hydrolysates were separated in under 20 minutes using these conditions. The time between injections was reduced to approximately one third of conventional run times, and quantitation was unaffected by the fast separation. Substitution of carbonate with acetate gave better resolution of wood sugars, but significant variations in retention time made the method unreliable. Seven sugars were surveyed for their suitability as internal standards with the fast separation technique. Of these, fucose was found to be the best.