Fluorescence spectrophotometry is widely used in the study of medicinal materials

1 Preface

With the changing mindset of the masses in today's society, traditional Chinese medicine has gradually become a hot topic among the public. At present, the traditional Chinese medicine market is mixed with good and bad, with fake and inferior medicines emerging one after another. The quality evaluation and quality control of traditional Chinese medicine in the Chinese medicine market are the means to ensure the effectiveness and safety of traditional Chinese medicine, but they have also been the bottleneck that has plagued the modernization development of traditional Chinese medicine. Firstly, the quality of traditional Chinese medicine is influenced by multiple factors and links. There are a wide variety of traditional Chinese medicinal materials, with scattered production areas. In addition, factors such as growth environment, harvest season, and processing technology result in differences in their chemical composition.

With the continuous development of traditional Chinese medicine, the advantages of fluorescence analysis in the identification of Chinese medicinal materials have gradually emerged. Chinese medicinal materials contain various chemical substances with fluorescent properties, such as cyclic compounds, aromatic compounds, etc. Leaf medicinal materials are difficult to identify due to their tendency to shrink and break during harvesting, processing, transportation, and storage; Due to the high content of tannins, chlorophyll, and other components in leafy medicinal materials, it is generally difficult to identify them through physical and chemical methods. It can be easily and quickly identified by fluorescence method.

2、 Identification of senna leaf and daqingye by fluorescence spectrophotometry

Senna leaves are a common laxative widely used in various tea drinks. Its sources are mostly imports, with relatively low domestic production, leading to the proliferation of counterfeit and inferior products. Currently, the application of large green leaves is chaotic, and the quality in the market varies greatly. And with the inclusion of Da Qing Ye in the list of drugs for preventing H1N1 by the Beijing Municipal Drug Administration, the usage of Da Qing Ye has increased dramatically, leading to a large number of counterfeit products being mixed up and used in the market.

Wang XinruiThe extraction solution was obtained by crushing senna leaves and large green leaves, adding water, dilute ethanol, methanol, dilute hydrochloric acid, and sodium hydroxide solution, followed by ultrasound and centrifugation. After consulting the information, set the excitation wavelength to 254nm and 365nm

Figure 1 and 2 Fluorescence spectra of different solvents for ultrasound excitation at 254nm wavelength of Da Qing Ye

Ultrasonic excitation wave 254nm fluorescence spectra of different solvents in senna leaves

Figure 3: Fluorescence spectra of different solvents for ultrasound excitation at 365nm wavelength of Da Qing Ye

Fluorescence spectra of senna leaves under ultrasound excitation with different solvents at 365nm wavelength

This study found that，Different spectra can be obtained from the extracts of two medicinal herbs using a fluorescence spectrophotometer. When the excitation wavelength is 254nm, there are two fluorescence peaks in the water and hydrochloric acid extracts of Da Qing Ye, while there is only one fluorescence peak in both senna leaves; When the excitation wavelength is 365nm, there are two fluorescence peaks in the methanol, sodium hydroxide, and ethanol extracts of senna leaves, while there is only one fluorescence peak in the large green leaves. And the fluorescence peak intensity of large green leaves is significantly stronger than that of senna leaves.

3、 Determination of riboflavin concentration in goji berries by fluorescence spectrophotometry

Riboflavin, also known as vitaminB2British chemist Bruce first discovered it from whey. Riboflavin is an essential nutrient for maintaining the normal functioning of the body, with multiple physiological functions. It can promote the metabolism of various organic compounds and promote the growth and development of the body. It participates in the metabolism of proteins, fats, and carbohydrates in the body, and is also related to animal vision. It is an essential nutrient for animals.The most widely used method for determining riboflavin concentration in today's society is fluorescence spectrophotometry,Fluorescence method utilizes riboflavin inpH4～9ofenvironmentBelow, the excitation wavelength is440～500nmThe principle of generating yellow green fluorescence within a certain range, and the fluorescence intensity being proportional to the concentration of riboflavin, is used to measure the fluorescence intensity of riboflavin. The method is simple and easy to operate.

Song Jiying and others added hydrochloric acid solution to goji berries, centrifuged them, and filtered the upper clear liquid. Pour the filtrate into a colorimetric dish and set the parameters:

Figure 5 Fluorescence intensity at excitation wavelengths of samples extracted from different hydrochloric acid solutions

Figure 6 Fluorescence intensity at excitation wavelength of samples extracted with different material to liquid ratios

Figure 7 Fluorescence intensity of excitation wavelength extracted samples at different stirring times

Through experiments with different control groups, the research group obtained the optimal experimental conditions. The research group accurately weighed 1.000g of riboflavin standard and used 1000ml of 0.5% acetic acid as the mother liquor. The mother liquor was then transferred to prepare riboflavin standard solutions at concentrations of 0.2, 0.4, 0.6, 0.8, and 1 μ g/ml. The standard working curve was plotted with riboflavin concentration as the x-axis and excitation wavelength fluorescence intensity as the y-axis. The obtained standard curve equation was F=15.998c+0.7684, where F was the fluorescence intensity, c was the riboflavin concentration, and the linear correlation coefficient was r２=0.9993.

4、 Product recommendation

Figure 8 ATF4500 Fluorescence Spectrophotometer

1) Overview: A fluorescence spectrophotometer is an instrument used to scan the fluorescence spectrum emitted by liquid phase fluorescent markers. It can provide many physical parameters including excitation spectrum, emission spectrum, fluorescence intensity, quantum yield, fluorescence lifetime, fluorescence polarization, etc., reflecting the bonding and structure of molecules from various perspectives. By measuring these parameters, not only can general quantitative analysis be conducted, but also conformational changes of molecules in various environments can be inferred, thereby elucidating the relationship between molecular structure and function. Can be used for scanning liquid and solid samples.

In response to the issue of decreased performance of instrument light sources over time, the ATF4500 adopts a xenon lamp with superior performance and improves the lamp power supply. The brightness of the light source has been increased, effectively extending the service life of the xenon lamp to 1000 hours. Extending the bulb replacement cycle can reduce consumable costs and alleviate the workload of bulb replacement and other related tasks. Paired with the advanced technology and brand new technology that have been developed by AOPU Tiancheng for a long time, the scientifically designed optical path system ensures the precision and determination accuracy of fluorescence analysis, while ensuring accurate results. The high-speed 3D fluorescence acquisition also ensures high-speed scanning speed. In addition, there are various accessories to choose from to meet the various measurement needs of users.

This product is equipped with AOPU Tiancheng's unique and simple operation page. From the user's perspective, the intelligent integrated system only requires a little training to enable users to quickly get started. In terms of data processing, online spectral processing can be used to better organize data.

2) Product selection

3) Product parameters

5 References

[1] Wang Xinrui, Feng Shuai, Li Feng Fluorescence identification of senna leaf and big green leaf medicinal materials [J]. Journal of Shandong University of Traditional Chinese Medicine, 2021, 45 (01): 125-132. DOI: 10.16294/j.cnki. 1007-659x. 2021.01.020

[2] Song Jiying Determination of riboflavin content in wolfberry by fluorescence spectrophotometry [J]. Chemical World, 2012, 53 (12): 720-722. DOI: 10.19500/j.cnki. 0367-6358.2012.12.005

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