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食品重金属污染日趋严重,为了探索激光诱导击穿光谱(LIBS)在农产品质量安全检测领域的应用价值,以实验室污染处理的含镉(Cd)大米为例,采用共轴双脉冲激光诱导击穿光谱(DP-LIBS)装置并对实验中的关键条件参数进行优化,探讨了DP-LIBS在提高农产品重金属检测灵敏度与准确度方面的可行性。采用LIBS技术和阳极溶出伏安法,获取9个浓度梯度的含Cd大米样品的LIBS光谱及Cd元素真实浓度信息,再采用一元线性定标回归模型,对Cd的三个特征光谱进行定量分析。结果表明,DP-LIBS能够检测到实验大米样品中Cd元素的最低质量比为5.03μg/g,Cd元素特征谱线强度与其浓度拟合直线均具有较高的线性相关性。研究表明,DP-LIBS能够提高Cd元素的检测灵敏度与准确度,并可通过一元线性回归模型得到Cd的浓度信息。
In order to explore the application value of laser-induced breakdown spectroscopy (LIBS) in the field of quality and safety testing of agricultural products, taking the contaminated cadmium (Cd) rice in laboratory as an example, the coaxial dual pulse laser-induced breakdown (DP-LIBS) device and optimize the key parameters in the experiment. The feasibility of DP-LIBS in improving the detection sensitivity and accuracy of heavy metals in agricultural products was also discussed. Using LIBS and anodic stripping voltammetry, the LIBS spectra and the true Cd concentration information of nine Cd-containing rice samples with different concentration gradients were obtained. The three characteristic spectra of Cd were quantitatively analyzed by using the linear regression model. The results showed that DP-LIBS could detect the lowest mass ratio of Cd in the experimental rice sample was 5.03μg / g, and the linear correlation between the intensity of Cd elemental characteristic line and its fitted curve of concentration was high. The results show that DP-LIBS can improve the detection sensitivity and accuracy of Cd, and obtain the Cd concentration information by a univariate linear regression model.