The kit assay will only measure the non-covalently linked monosaccharide. Oligosaccharides or polysaccharides can be measured after hydrolysis to the monosaccharide. Generally acid hydrolysis can be achieved by boiling the oligo/polysaccharide in 1.3 M HCl for 1 h (please see below for detailed procedure). It is recommended that scientific literature is consulted for information on hydrolysis conditions for the particular oligo/polysaccharide that is being measured.
Determination
of D-glucose in polysaccharides and fibrous plant material:
Mill plant material or polysaccharide to pass a 0.5 mm screen using a Retsch centrifugal mill, or similar. Accurately weigh approx. 100 mg of material into a Corning screw-cap culture tube (16 x 125 mm). Add 5 mL of 1.3 M HCl to each tube and cap the tubes. Incubate the tubes at 100˚C for 1 h. Stir the tubes intermittently during the incubation. Cool the tubes to room temperature, carefully loosen the caps and add 5 mL of 1.3 M NaOH. Quantitatively transfer the contents of the tube to a 100 mL volumetric flask using distilled water and adjust the volume to 100 mL with distilled water. Mix thoroughly by inversion and filter an aliquot of the solution through Whatman No. 1 filter paper or centrifuge at 1,500 g for 10 min. Typically, no further dilution is required and a sample volume of 0.1 mL is satisfactory.