含水量对LIBS检测土豆中Pb元素灵敏度的影响

摘要

农产品重金属污染问题越来越严峻，急需发展一种快速检测新方法。激光诱导击穿光谱（ LIBS）是近年来兴起的物质成分快速无污染的分析方法。但由于农产品成分复杂，受到含水量、有机质元素等复杂基体的影响，导致LIBS在农产品检测方面的研究还缺乏系统的分析。本工作以实验室配置的含铅（ Pb）污染的土豆样品为例，通过LIBS技术对不同含水量土豆中的Pb元素进行了检测，探讨了含水量对土豆中铅元素灵敏度的影响。试验结果表明含水量对LIBS信号有明显的干扰，样品越干燥，灵敏度越高。对完全干燥的土豆样品进行了LIBS光谱采集和Pb含量原子吸收光谱（ AAS）真实浓度检测，建立了Pb元素真实浓度与其LIBS强度关系模型，定标结果显示模型具有较好的相关系数。研究说明LIBS对Pb污染严重的土豆样品具有一定的检测可行性，对于低浓度的样品，检测能力仍有很大的提升空间。%Pollution from heavy metals in agricultural products is becoming more and more serious. It is very necessary to develop a novel technology for rapid detection. Laser Induced Breakdown Spectroscopy ( LIBS) is a new method in analysis of composition,and it can achieve fast and environmentally friendly deter⁃mination . Systematic research is not enough in monitoring farm products by LIBS due to complicate matrix effect of samples.In this work,potatoes polluted in lab were chosen as the target.LIBS spectra of samples with differ⁃ent water contents were collected,and the effect of water on sensitivity of LIBS signal was analysed.The results showed that water plays an important role in sensitivity of LIBS. It is easy to detect the spectroscopy in drier samples.For Pb polluted dry samples,the spectra were gained by LIBS and the content of Pb was acquired by AAS.The linear relationship between LIBS intensity and AAS content was constructed.The results demonstrated that the correlation coefficient was preferable.This work displayed that it is feasible to detect Pb in potato.But about the natural samples with lower content of Pb,it is significant to improve the ability of LIBS in direct anal⁃ysis without any pretreatment.