Pulp pentosan content can be determined using the phenol-sulfuric acid colorimetric method. The following are the specific operation steps:
principle
Add the pulp sample into the phenol sulfuric acid reagent, the pentosose decomposes to glucose, and reacts with phenol to form a red compound, then measure the absorbance of the solution with a UV-visible Spectrophotometer or a Colorimeter, and calculate the concentration of the pentosan in the sample through the standard curve content.
Instruments and Reagents
Phenol-sulfuric acid reagent: Add 50 grams of phenol and 400 ml of concentrated sulfuric acid into 1 liter of water, mix well and add to 1 liter of 95% ethanol, mix well and then use.
Pentosan standard: prepared with purified water, the concentration is 1mg/mL.
UV-Vis Spectrophotometer or Colorimeter.
Routine laboratory equipment: pipettes, cuvettes, magnetic stirrers, etc.
Steps
Prepare a series of pentosan standards with different concentrations, and establish a standard curve by the phenol-sulfuric acid colorimetric method.
Take a certain amount of pulp sample, add an appropriate amount of phenolic sulfuric acid reagent, mix well, place in a Water Bath and heat to 80-90°C, and react for 15 minutes.
After cooling, dilute with pure water to the appropriate absorbance range, and then measure the absorbance of the solution with a UV-visible Spectrophotometer or a Colorimeter.
The content of pentosan in the pulp samples was calculated by the standard curve.
North and South Chao reminds you: this method has little effect on other components such as lignin, hemicellulose, etc., but it will be affected by other polysaccharides, so appropriate sample pretreatment and correction are required.
