茶叶中铬的激光诱导击穿光谱快速检测及等离子体参数

Fast Quantitative Analysis and Spectroscopy Characteristics of Cr in Tea by Laser Induced Breakdown Spectroscopy

本文利用Nd:YAG激光器、中阶梯光栅光谱仪和CCD,自行搭建激光诱导击穿光谱实验平台(laser induced breakdown spectroscopy,LIBS),获取重金属元素Cr等离子体谱线。实验结果表明,茶叶中的重金属元素Cr位于427.48nm处,特征谱线强度好,适合定量分析,谱线强度和样品浓度建立的标定曲线方程为y=2.784x-65.103,相关系数r为0.9910,理论最低检测限为7.63μg·g^(-1),样品回收率90.0%～131.3%。含Cr茶叶样品受激发产生等离子体的温度为11592.93 K,电子密度为2.65×10^(19) cm^(-3),等离子体满足局域热动平衡条件。LIBS可以用于茶叶中铬的快速测定。

Laser induced breakdown spectroscopy(LIBS)was built by using a Nd:YAG laser and an echelle grating spectrometer with CCD in order to get Cr plasma spectral lines.It was shown that the characteristic spectrum of Cr at 427.48 nm was strong and selected for detection.The calibration formula y=2.784x-65.103 was established between the intensity of the spectral lines and Cr concentrations in tea samples,with the correlation coefficient r was 0.9910,the limit of detection(LOD)was 7.63μg/g and recovery rate was 90.0%~131.3%.From the characteristic spectra obtained by Cr-contained tea,the temperature and density of the plasma induced by laser were calculated to be 11592.93K and 2.65×10^19/cm^3,respectively.The plasma was in local thermodynamic equilibrium state.LIBS was successfully applied to fast detect Cr amounts in tea samples.