Sulfuric Acid Solubilization of Plant Biomass
Sulfuric acid is used in a two-step process to hydrolyze cellulose in plant cell walls. This hydrolysis is useful for total carbohydrate determination and/or analysis of Klaison lignin. This hydrolysis is based on the process developed by J. F. Saeman which was published in 1945. (Saeman, J. F. (1945) Ind. Eng. Chem. 37, 42–52.)
Concentrated sulfuric acid
Heating block set to 121˚C
Carefully weigh 10–15 mg of Alcohol Insoluble Residue from plant cell walls into a glass, screw cap tube.
In a 15mL falcon tube, carefully add 2.0 mL of concentrated sulfuric acid to 1.0 mL of deionized water. This will yield a 72% solution. Make this fresh each time.
When the acid has cooled to room temperature, pipette 500 μL into each sample aliquot. Vortex gently to ensure that the acid has saturated all the sample particles.
Incubate the samples at room temperature for 1 h.
Carefully add 4.5 mL of water to each sample and vortex well.
Place in a heating block set to 121°C and incubate for 1 h, mixing vigorously every 15–20 min.
Remove from heat and allow samples to cool to room temperature.
Soluble hydrolysates are ready for analysis.