Quantitative Analysis Of Cadmium And Copper In Gannan Navel Oranges Based On Laser-induced Breakdown Spectroscopy Technology

Green agricultural products are the focus that everyone concerns, the safety of which will directly effect human health. Heavy metal Cd and Cu along with pollutant discharged will be absorbed by agricultural products and finally enter into human body. And human health will be greatly effected due to the accumulation of Cd and Cu.Gannan navel orange is one of the symbols among the fruits in Jiangxi province. With the worsening the environment of navel orange, rapid and effective detection on the content of Cd and Cu in Navel becomes very crucial. So the content of Cd and Cu in navel based on laser induced breakdown spectroscopy which has great advantages in detecting heavy metal elements is analysed quantitatively. The laser induced breakdown spectroscopy experiment system was designed and built. The following investigations were made in this dissertation.Firstly, the LIBS system was built. In order to get a stable detecting environment and make the LIBS system has a good effect to detect heavy metal in agriculture products, the parameters such as the angle of optical fiber and focal point were adjusted.Secondly, the LIBS detecting parameters were optimized. Analyze the characteristic line position of cadmium and copper. The laser energy and delay time were optimized. The result indicate that optimum parameters of detecting Cd and Cu in navel are1300ns,130mJ and1200ns,120mJ.Finally, Cd and Cu in navel orange were analyzed quantitively with the optimized parameters. The navel orange samples were polluted by the copper sulfate and chloride cadmium solution, and there were each52samples with Cd and Cu. Then the LIBS spectra was collected, and the spectroscopic data was pretreated based on five-spot smoothing and centralized method. The concentration of Cd and Cu was detected through atomic absorption spectrophotometer. Quantitative detection model used to analyze the concentration of Cd and Cu in navel orange through partial least squares were built. Spectroscopic data of39samples was used to build model and the other was used to build model validation. The results show that models of the correlation coefficient of Cd and Cu elements were0.9806and0.9926, coefficient of association model validation were0.9939and0.9911, predicted detection limit were3～5μg/gand10～13μg/g.The results show that LIBS detecting heavy metals in Gannan navel orange was feasible, and the study for rapidly detecting heavy metals in agriculture produce by LIBS provides theoretical basis and technical support.