基于激光诱导击穿光谱的化肥成分检测方法研究

Rapid in situ and nondestructive detection of fertilizer component is the trend development of the fertilizer industry. Most detecting methods of fertilizer component are the on-site sampling and testing in laboratory, which is difficult to achieve accurate access to real-time information of fertilizer component. Although the near-infrared spectroscopy (NIR) can detect moisture, nitrogen, biuret and other ingredients in fertilizer, but the concentration of phosphorus and some metal elements were can’t be detected by NIR technique. In view of this, this project proposed a new quantitative analysis method of fertilizer component, which could achieve fast and accurate measurement of the concentration of fertilizer component in real-time.. This project will start from the real-time detection of high-sensitivity spectroscopy of fertilizer samples. The characteristics of laser-induced breakdown spectroscopy (LIBS) of fertilizer component will be analyzed. The impact mechanism and removal method of system parameters and environmental conditions on the spectral measurements will be studied, too. Based on the physical mechanism of laser plasma formation, the poor accuracy of the traditional calibration method led by the mutual interference of multi-element will be studied. And multivariate quantitative model will be established, which based on principal component analysis and weighted least squares method. Then using the method of experimental analysis, the model will be modified. Some issues of quantitative analysis of fertilizer component can be solved. This project will provide the basis for rapid in situ and nondestructive detection of fertilizer component.

化肥成分的快速原位及无损检测是化肥行业的发展趋势，目前化肥成分的检测方法，大多采用现场采样、实验室分析方法，难以获取化肥成分的在线实时信息。近红外光谱技术虽可检测化肥中水分、总氮和缩二脲等成分，但无法对化肥中磷和部分金属元素进行测量。鉴于此，本项目提出一种化肥成分检测新方法，可实现化肥成分的实时快速精确测量。. 项目将从化肥成分的高灵敏光谱实时检测入手，研究化肥成分的激光诱导击穿光谱特征；研究系统参数和环境条件对光谱测量的影响机制及去除方法；从激光等离子体形成的物理机制出发，研究多元素相互干扰导致传统定标方法的精确度差问题，建立基于主成分分析和加权最小二乘法的多变量定量模型，并利用实验分析手段对模型进行修正，解决化肥成分快速定量分析存在的问题。本项目的研究为实现化肥成分的快速原位及无损检测奠定了基础。

我国是世界上最大肥料生产国和消费国，肥料产品的质量检验非常重要。由于化肥检测的样本量非常大,传统意义上的测量方法要么不够准确,要么检测工作量大影响效率,故急需要发展一种快速检测方法来对化肥进行精确的测量。与传统现场采样、实验室检测方法相比，激光诱导击穿光谱(LIBS)技术提供了一种化肥快速、现场分析的新方法，具有分析简便、几乎无需样品预处理、多元素同时测量等优点，开展化肥成分的LIBS检测方法研究具有重要的应用价值。. 本项目针对LIBS技术检测化肥成分所面临的问题开展了大量研究工作，圆满完成了计划书中规定的目标和任务。首先描述了化肥成分激光诱导击穿光谱测量原理、系统组成及元素分析线的选取，通过对分立光谱的时间、空间演化特性的分析，探讨了化肥激光等离子体形成过程中谱线的形成机制；重点研究了系统参数（激光能量、重复频率、焦点位置）与化肥样品的粒径、疏松度等对激光等离子体谱线强度、信背比、等离子体温度、电子密度以及测量信号稳定性的影响；并分析了自然大气与氩气环境下激光等离子体的时间演化特性及元素检测灵敏度。. 在理论与实验研究的基础上，通过对不同元素特征谱线的特性分析，确定了最佳的延时探测时间和门控宽度，对K、N、P三种元素的检测限进行了分析；综合比较研究了定标曲线法、内标法、多元非线性回归法、支持向量机在定量分析中的优劣，开发了包括系统控制、数据处理与定量分析软件。进行了化肥成分LIBS检测装置的的联合调试、模型验证等试验。研究结果为发展化肥成分的快速、在线检测技术提供了数据基础和方法。