| With the improvement of people's living quality and protection consciousness,more and more people pay close attention to public health,One of the important part is smoking.As we all know smoking is harmful to health,It will be more serious if there are harmful to human body elements in tobacco leaves.It becomes relevant government departments and scientific research institution is more and more concern about How to reduce the population and improve the quality of tobacco,for Reducing the damage to a minimum from tobacco.Element in tobacco can enter the body by combusting absorption,Heavy metal elements in human body can accumulate and produce different degree of harm to human body,so it is great necessary to improve the quality of tobacco leaf.It needs to explore a kind of real-time monitoring the growth of tobacco leaves to improve the quality of tobacco leaves,However the traditional element detection method almost is Atomic absorption spectrometry,This method can not be satisfied with detection of tobacco leaves growth because of tedious pretreatment and long cycle time.So it is very valuable to research a method which can rapid,efficient and accurate in detecting element.The characteristics of Laser Induced Breakdown Spectroscopy is simple pretreatment,wide detection range and high precision,The technology is widely used in environmental monitoring,agriculture and life science,etc.thesis analyzes differences between Traditional detection methods and Laser Induced Breakdown Spectroscopy in detection tobacco leaf elements.Experiment results show that laser induced breakdown spectroscopy method can be applied to tobacco online detection of metal elements.The paper main research content includes the following several parts:1.building LIBS experiment system.This experiment system is mainly composed of Nd: YAG pulsed laser,optical system,sample room,plasma spectrum signal collection fiber,echelle spectrograph and enhanced the CCD and synchronous sequential control time delay of controller.experiment optimization Lay the foundation for research work,The paper argument fasibility and precision in element detection by laser induced breakdown spectroscopy method.2.Experimental analysis of Cd elements in tobacco leaves by laser induced breakdown spectroscopy.The experimental elements were added to the experimental tobacco leaves according to a certain proportion,and the samples were sampled at different positions,and the average was taken as the final spectral.Establish Cd element concentration and spectral calibration curve,and judge the accuracy of calibration curve.3.Quantitative analysis of calibration curve and the study of plasma by Laser Induced Breakdown Spectroscopy,Experimental samples selected from high-quality tobacco leaf in fuzhou.several tobacco samples containing Cu in arranged from 8.59?g·g-1 to 156.35?g·g-1 were prepared.The Cu amounts prepared in laboratory were measured by using atomic absorption spectroscopy.Experiments indicate that Cu characteristic spectrum in the wavelength of 324.75 nm is quite clear,and easy to obtained.From the characteristic spectra obtained from Cu-contained sample,the temperature and the density of the plasma induced by laser are calculated to be 39458.94 K and 0.74×1016,respectively.The fitting curve with the correlation coefficient(R square)of 0.98 was established from the relationship between the intensity of the spectral lines and the sample concentrations,The mean of the relative standard deviation(RSD)of 2.59% was obtained.Furthermore,limit of detection(LOD)of 7.72?g·g-1 and the ratio of signal to noise of 7.86 were calculated,respectively from the tobacco leaves.The method was successfully applied to predict the Cu amounts in tobacco samples,with the potential to be used in cigarette production lines and in tobacco breeding.Research lays a preliminary basis for LIBS technology applied in tobacco leaf element detection. |
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