Acidic hydrolysis of the residues and subsequent
catalytic oxidation with H2O2 under alkaline conditions:
2.5 g of the solid and 25ml of 2M HCl were filled in a
digestion apparatus as described above and reacted under
reflux and stirring for 12 h. After that the mixture
was filtered, neutralized with NaOH and diluted to
50ml with distilled water. To oxidize the monosaccharides,
2.5ml of H2O2, 625mg of Na2CO3 and 62.5mg
of CuO were added and then the mixture was reacted
under agitation in a water bath at 60C for 4 h. Finally,
the CuO particles were removed by filtration and the
solution was neutralized to pH 7 with HCl solution then
diluted to 100ml with distilled water.