猪肉中典型重金属元素的双脉冲激光诱导击穿光谱检测研究

发布时间：2019-03-12 20:02

【摘要】：我国是世界猪肉生产和消费第一大国,而生猪在养殖、屠宰、流通过程都有被重金属污染的可能,猪肉重金属残留量也是食品卫生安全要求的必检项目。传统化学分析方法的前处理繁琐且会对环境造成污染,因此需要探索绿色检测方法。激光诱导击穿光谱(Laser induced breakdown spectroscopy,LIBS)是一种具有绿色、快速、原位检测特点的发射光谱检测技术,可以满足绿色在线检测需求。本工作利用双脉冲激光诱导击穿光谱(Dual-pulse laser induced breakdown spectroscopy,DP-LIBS)对猪肉中典型重金属元素镉(Cd)、铅(Pb)和铬(Cr)进行快速绿色检测研究,进一步结合微波辅助双脉冲LIBS(Microwave assisted dual-pulse laser induced breakdown spectroscopy,MA-DP-LIBS)检测猪肉标准物质样品中的重金属元素Cd和Pb,探究微波对LIBS光谱中Cd和Pb的增强效果。论文主要研究内容如下:以猪肉样品中典型重金属元素Cd、Pb、Cr为研究对象,结合LIBS光谱数据与目标元素浓度进行定量分析。对试验样品进行DP-LIBS测试后,分别采用阳极溶出伏安法(Anodic stripping voltammetry,ASV)和原子吸收光谱法(Atomic absorption spectrometry,AAS)检测得到样品中Cd和Pb、Cr浓度。将Cd、Pb强度值与浓度值进行单变量线性拟合,拟合系数分别为0.90、0.55。在标准正态变量变换(Standard normal variable transformation,SNV)、一阶导数(First derivative,FD)、二阶导数(Second derivative,SD)、多元散射校正(Multiple scattering correction,MSC)和均值中心化(Mean centralized,MC)五种预处理方法中选择最佳预处理方法MC,分别进行偏最小二乘(Partial least squares,PLS)、间隔偏最小二乘(Interval partial least squares,iPLS)和联合间隔偏最小二乘(Synergy interval partial least squares,Si PLS)建模,以交叉验证均方根误差(RMSECV)、预测均方根误差(RMSEP)、对应的训练相关系数(RC)、预测相关系数(RP)为检验标准对LIBS光谱数据进行分析比较。结果显示,三种元素的拟合系数均达到0.95以上,Cd拟合最佳效果高达0.9986。结论表明,PLS、i PLS和SiPLS模型均可对猪肉中Cd、Pb、Cr进行分析,这为猪肉中重金属元素LIBS检测提供了参考依据。结合MA-DP-LIBS对猪肉标准物质样品中重金属元素Cd、Pb进行检测研究。结果显示,采用猪肉标准物质代替原始猪肉可使Cd、Pb的干样浓度最低检出限由11.10mg/kg、8.58 mg/kg降低为9 mg/kg、4 mg/kg,且MA-DP-LIBS对大部分元素增强效果显著,而Cd在MA-DP-LIBS测试下会受到其它基质元素干扰导致谱线被覆盖。结论表明,MA-DP-LIBS对猪肉标准物质中Pb元素有信号增强效果。
[Abstract]:China is the world's largest country in pork production and consumption, and pig breeding, slaughtering, circulation process are likely to be contaminated by heavy metals, pork heavy metal residue is also a food hygiene and safety requirements of the necessary inspection items. The pretreatment of traditional chemical analysis methods is cumbersome and will pollute the environment, so it is necessary to explore green detection methods. Laser-induced breakdown spectroscopy (Laser induced breakdown spectroscopy,LIBS) is a green, fast, in-situ emission spectrum detection technique, which can meet the needs of green on-line detection. In this work, double pulse laser induced breakdown spectroscopy (Dual-pulse laser induced breakdown spectroscopy,DP-LIBS) was used to detect the typical heavy metal elements CD, (Cd), Pb, (Pb) and Cr-(Cr) in pork. The enhancement of Cd and Pb in LIBS spectra by microwave assisted double pulse LIBS (Microwave assisted dual-pulse laser induced breakdown spectroscopy,MA-DP-LIBS (microwave assisted double pulse Cd) detection of heavy metal elements (Cd and Pb,) in pork reference material samples was investigated. The main contents of this paper are as follows: taking the typical heavy metal element Cd,Pb,Cr in pork samples as the research object, the quantitative analysis was carried out by combining the LIBS spectral data with the concentration of the target elements. After DP-LIBS, the concentrations of Cd and Pb,Cr in the samples were determined by anodic stripping voltammetry (Anodic stripping voltammetry,ASV) and atomic absorption spectrometry (Atomic absorption spectrometry,AAS), respectively. The linear fitting coefficients of Cd,Pb intensity and concentration were 0.90,0.55 respectively. In standard normal variable transformation (Standard normal variable transformation,SNV), first derivative (First derivative,FD), second derivative (Second derivative,SD), multivariate scattering correction (Multiple scattering correction,MSC and mean centralization (Mean centralized, Among the five pretreatment methods, MC, (partial least Squares (Partial least squares,PLS), interval partial least Squares (Interval partial least squares,iPLS) and Joint interval partial least Squares (Synergy interval partial least squares,Si PLS) are selected to model MC). The training correlation coefficient (RC),) prediction correlation coefficient (RP) corresponding to the root mean square error (RMSEP),) prediction of root mean square error (RMSECV),) was used as the test standard to analyze and compare the LIBS spectral data. The results showed that the fitting coefficients of the three elements were above 0.95, and the best fitting effect of Cd was 0.9986. The results show that both PLS,i PLS and SiPLS models can be used to analyze the Cd,Pb,Cr in pork, which provides a reference for the detection of heavy metal element LIBS in pork. The determination of heavy metal element (Cd,Pb) in pork reference material samples by MA-DP-LIBS was studied. The results showed that the detection limit of Cd,Pb could be reduced from 11.10 mg / kg to 9 mg/kg,4 mg/kg, by using pork reference material instead of raw pork. Moreover, the enhancement effect of MA-DP-LIBS on most of the elements is remarkable, while the Cd will be interfered by other matrix elements under the MA-DP-LIBS test, and the spectral lines will be covered. The results showed that MA-DP-LIBS could enhance the signal of Pb in pork reference material.
【学位授予单位】：江西农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TS251.51;O657.3

【参考文献】