论文部分内容阅读
利用课题组自主研制的便携式激光诱导击穿光谱测量系统定量分析土壤及固体废弃物中四种重金属元素Pb,Cd,Cr和Cu。实验采用中心波长为1 064nm的Nd∶YAG脉冲激光器作为激发光源,工作频率为3Hz,单脉冲能量为100mJ,脉冲宽度为6ns;以高分辨率、宽光谱段的中阶梯光栅光谱仪和增强型电荷耦合器件为谱线分离与探测器件,探测范围为200~500nm,分辨率为0.08~0.12nm。为了提高光谱强度及检测灵敏度,通过半球空间约束装置对等离子进行约束,并采用多芯光纤实现多通道不同角度光谱信号收集,接收角度为45°。实验时激光重复频率为2Hz,延时为1.5μs,门宽为1.05ms。文章创新性地将曲线拟合代替直线拟合用于标准加入法定量分析基质未知样品中重金属元素,有效提高了测量结果的准确性,尤其是低浓度的土壤样品,直线拟合无法定量分析重金属含量,相比而言,曲线拟合相关系数更高,测量结果更接近国标方法,可以满足一级土壤污染的检测。七个土壤及固体废弃物样品检测的相对误差如下,直线拟合相对误差分别为:Pb 1.26%~79.38%,Cr-22.44%~82.06%,Cu 15.09%~190.50%,Cd 32.76%~167.96%,曲线拟合相对误差为分别Pb-4.19%~11.92%,Cr-38.31%~9.26%,Cu-7.24%~26.86%,Cd-10.52%~12.94%,相对误差平均值为10.47%。
Quantitative Analysis of Four Heavy Metals Pb, Cd, Cr and Cu in Soils and Solid Waste Using Portable Laser Induced Breakdown Spectroscopy System Developed by the Research Group. The experiment uses Nd: YAG pulsed laser with the center wavelength of 1 064 nm as the excitation light source, the working frequency is 3 Hz, the single pulse energy is 100 mJ and the pulse width is 6 ns. The high-resolution, wide-spectrum middle-stepped grating spectrometer and enhanced charge Coupling device for the spectral line separation and detection devices, detection range of 200 ~ 500nm, a resolution of 0.08 ~ 0.12nm. In order to improve the spectral intensity and detection sensitivity, the plasma is confined by the hemispherical space constraining device, and multi-core optical fiber is used to collect multi-channel spectral signals of different angles with a receiving angle of 45 °. Experimental laser repetition frequency of 2Hz, delay of 1.5μs, the door width of 1.05ms. In this paper, instead of using a straight line fitting curve fitting instead of standard addition method for quantitative analysis of unknown heavy metals in the matrix samples effectively improve the accuracy of the measurement results, especially in low concentrations of soil samples, linear fit can not be quantitative analysis of heavy metals Compared with the curve fitting, the correlation coefficient of the curve fitting is higher, and the measurement result is closer to the national standard method, which can meet the requirement of soil contamination testing of the first grade. The relative errors of the soil and solid waste samples were as follows. The relative errors of the straight line fitting were Pb 1.26% -79.38%, Cr-22.44% -82.06%, Cu 15.09% -19.50%, Cd 32.76% -167.96% The relative error of curve fitting is Pb-4.19% ~ 11.92%, Cr-38.31% ~ 9.26%, Cu-7.24% ~ 26.86% and Cd-10.52% ~ 12.94%, respectively. The relative error is 10.47%.