Determination of lignin content in raw materials and pulps using UV spectroscopy is a commonly used method. The basic principle is that the aromatic ring in the lignin molecule can absorb ultraviolet rays, and different types of lignin differ in absorption wavelength and intensity. Therefore, by measuring the absorbance of the sample in the ultraviolet spectral range, the lignin content in the sample can be determined.
The specific operation steps are as follows:
Take a certain amount of sample (such as pulp or raw material) and dissolve or suspend it in an appropriate solvent (such as methanol or ethanol).
Using a UV Spectrophotometer , measure the absorbance of the sample over a specific wavelength range (typically 200-400 nm). Pure solvent is required as a blank control.
Analyze the data and calculate the lignin content of the sample. The lignin content is usually determined using a colorimetric method or a standard curve method. The standard curve method needs to prepare a series of lignin standard solutions with different concentrations, and then use an ultraviolet Spectrophotometer to measure the absorbance of each standard solution to obtain a standard curve. By comparing the sample absorbance with the standard curve, the lignin content in the sample can be calculated.
Beichao reminds you: In the actual operation process, there may be some interfering substances, such as cellulose and pigments, which may affect the measurement results. Therefore, pretreatment of the sample is required, such as filtering with filter paper or adding appropriate chemicals for removal. In addition, it is also necessary to select an appropriate solvent and wavelength range to improve the accuracy and precision of the determination.
