蔬菜中Ca含量的LIBS快速检测研究

Rapid Detection of Ca in Vegetables by LIBS

蔬菜中矿质元素含量是评价其质量安全的一项重要指标。为了实现对蔬菜中矿质元素的快速检测,采用激光诱导击穿光谱(LIBS)装置对国家标准成分蔬菜样品中的Ca元素进行分析,获取样品的LIBS图谱,并分别建立样品Ca元素真实浓度与其LIBS特征谱线Ca II 315.887和Ca II 317.933强度之间的关联模型。结果表明,LIBS能清晰探测出样品中高浓度的元素;但对于低浓度的重金属元素,检测灵敏度达不到要求。可以看出,Ca元素定量分析模型线性相关性较好;对于高浓度的叶菜类蔬菜,Ca元素含量的预测准确度较高;但对于低浓度的根茎类和果实类蔬菜,模型预测准确度较差。该试验说明,LIBS用于检测具有复杂基体的蔬菜样品时,对元素的检测效果较好,是否单纯检测某类别(比如叶菜类)的蔬菜样品受基体效应的影响更小,从而提高检测精度,有待于进一步研究。

The varieties and contents of mineral elements are the most important indexes in evaluating the quality and safety of vegetables.It is necessary to detect the components in vegetables by rapid means. In this work,the vegetable samples from Chinese Reference Materials were analyzed by laser induced breakdown spectroscopy（ LIBS） constructed in the lab.The spectra of samples were collected.Aiming at Ca,Ca II 315.887 and Ca II 317.933 were chosen as the characteristic line.At the same time,the model between LIBS intensity and concentration about objective element Ca was established.The results showed that the mineral elements of high contents could be detected by LIBS clearly,but heavy metals of high contents could not be tested by LIBS.The quantitative model had good linear correlation. The predicted accuracy of higher Ca content in leaf vegetables was better.It is worth noting that vegetables have complex matrix effect. Maybe it is not suitable to predict the contents of minerals by simple model.In the next work,some endeavor should be done in determining concrete vegetables,such as leaf vegetables,to eliminate the effect of matrix.