Detection Of Sulfur Dioxide Content In Chinese Medicinal Materials Based On UV Absorption Broad Spectrum

Chinese herbal medicine plays an important role in the prevention and treatment of diseases,and has been widely used at China and abroad.Sulfur fumigation is a traditional Chinese medicinal material processing method with a long history,which can not only prevent insects and preservatives,prolong the shelf life,but also bleach and brighten the medicinal materials to make them look better.However,in order to obtain more profits,some drug dealers abuse or overuse sulfur fumigation,which will not only lead to the failure of some active ingredients in the medicinal materials,but also the main residual sulfite after sulfur fumigation will cause different degrees of damage to the body.Therefore,in order to ensure the edible safety of Chinese herbal medicines,it is imperative to quickly and accurately detect the sulfur dioxide content of Chinese herbal medicines.At present,the main methods for detecting sulfur dioxide content in Chinese medicinal materials include titration,test paper,chromatography,and spectrophotometry.Although the titration method and the test paper method are simple and economical,they are greatly influenced by the operator and have low detection accuracy;Chromatography and spectrophotometry have high accuracy,however,they are not conducive to grass-roots development due to their high detection cost,complex operation process,and high degree of professionalism.Therefore,it is necessary to find a simple,accurate and economical detection method.Benefiting from the advantages of optical detection with high detection accuracy,strong selectivity and high sensitivity,this paper proposes to use ultraviolet absorption spectroscopy to detect the content of sulfur dioxide in Chinese medicinal materials.In this paper,built a sulfur dioxide detection system based on ultraviolet absorption spectrum,and detected the content of sulfur dioxide in traditional Chinese medicinal materials by using yam powder as the sample to be tested,which has practical significance and commercial value.The main content of this article is as follows:1.Starting from the actual application scenario,combined with the system detection requirements,the overall scheme of the detection system for sulfur dioxide content in Chinese medicinal materials is designed,and the system distillation part,filtration and dehumidification design,overall hardware circuit design and the denoising of the signal are described in detail.This system uses a 0.1 μm double-layer hydrophobic polytetrafluoroethylene filter membrane to filter out macromolecular particles.After trying and comparing a variety of dehumidification methods,the dehumidification method of membrane drying tube combined with condensation and cooling is used to basically remove the water vapor brought by the driving gas;In terms of denoising,the demy wavelet global default threshold algorithm is used to reduce the noise from 16.8 mV to 6.2 mV;2.Based on the demand for the detection of sulfur dioxide content in Chinese medicinal materials,the sulfur dioxide detection system was evaluated from three aspects of stability,linearity and response time using sulfur dioxide standard gas.The results show that the long-term stability of the system is good,the fluctuation is small after stability;When introducing different concentrations of sulfur dioxide standard gas,the correlation coefficient R2=0.9954,indicating that the system has good linearity,and the detection limit is 5 ppm(5 parts per million);The response speed is fast,the fall time is 15 s,and the recovery time is 12 s,which meets the actual test requirements.3.Taking yam powder as the sample to be tested for distillation,the change of the voltage signal curve of the system during the distillation process was analyzed.After repeated experiments,the experimental results show that the system has good reproducibility;At the same time,based on Henry’s Law and Dalton’s Law,the final desorption conditions of the system were determined from the two aspects of H+concentration and gas-liquid ratio;Weigh the same batch of yam powder with different weights to carry out the experiment,the results show that there is a good linear relationship between the weight of yam powder and the total amount of desorption of sulfur dioxide,and the correlation coefficient R2=0.9937;During further analysis and exploration,it was found that there is also a good linear relationship between the weight of yam powder and the valley voltage of the voltage signal curve,and the R2 is 0.9944.Since the time to obtain this valley voltage is short(the first 15-18 min of the distillation experiment)and the signal-to-noise ratio is high,this relationship also provides a new idea for the rapid detection of sulfur dioxide content in yam powder.