Hemicellulose content

By Allschoolabs
• Published on August 2, 2025
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Category: Analytical
  • Last updated: August 2, 2025

The term alpha cellulose describes that part of cellulose which does not dissolve in 17.5% sodium hydroxide solution. Alpha cellulose can be determined according to Zellcheming Merkblatt IV/29 A. About 3 g (exactly weighed) of the sample (either pulp or holocellulose obtained from the raw material) are put in a porcelain beaker (250 ml), then 25 ml of 17.5% NaOH are added and the sample is left to swell for 4 minutes (time was exactly measured from the last drop), and then pressed with a glass rod for 3 minutes. After pressing, another 25 ml of sodium hydroxide are added and mixed thoroughly till a homogeneous paste is obtained (mixing for about 1 minute). The beaker is then covered and left for 35 minutes at 20°C. 100 ml of distilled water are then added and the material is quickly filtered under suction using a sintered glass funnel. The filtrate is then poured on the paste twice before washing with distilled water. After washing with distilled water till neutrality 100 ml of 10% acetic acid are added dropwise followed by distilled water.

Cellulose

This is calculated as:

Cellulose = 100% – (Hemicellulose + lignin + Ash)

Holocellulose estimation

Holocellulose is the total carbohydrate fraction (cellulose and hemicellulose) of the raw material as was estimated according to Wise et al., 1946.

The term alpha cellulose describes that part of cellulose which does not dissolve in 17.5% sodium hydroxide solution. Alpha cellulose can be determined according to Zellcheming Merkblatt IV/29 A. About 3 g (exactly weighed) of the sample (either pulp or holocellulose obtained from the raw material) are put in a porcelain beaker (250 ml), then 25 ml of 17.5% NaOH are added and the sample is left to swell for 4 minutes (time was exactly measured from the last drop), and then pressed with a glass rod for 3 minutes. After pressing, another 25 ml of sodium hydroxide are added and mixed thoroughly till a homogeneous paste is obtained (mixing for about 1 minute). The beaker is then covered and left for 35 minutes at 20°C. 100 ml of distilled water are then added and the material is quickly filtered under suction using a sintered glass funnel. The filtrate is then poured on the paste twice before washing with distilled water. After washing with distilled water till neutrality 100 ml of 10% acetic acid are added dropwise followed by distilled water. Cellulose This is calculated as: Cellulose = 100% – (Hemicellulose + lignin + Ash) Holocellulose estimation Holocellulose is the total carbohydrate fraction (cellulose and hemicellulose) of the raw material as was estimated according to Wise et al., 1946.