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为快速、安全地检测氧乐果和毒死蜱农药残留,使用改进的氯化钯比色法,分别采集2种农药比色反应后的吸收光谱,利用主成分分析法(PCA)和偏最小二乘法(PLS)建立预测模型。结果表明:1)使用乙酸代替传统浓盐酸配制的氯化钯比色试剂效果更理想,氧乐果和毒死蜱的吸收光谱可以区分的检测下限分别是0.05和0.50mg/L,基本满足GB 2763—2014对部分果蔬的检测要求。2)氧乐果和毒死蜱吸收光谱的敏感波长分别为510和499nm,由此确定最优建模波段。对比PCA和PLS方法建模效果,2种农药的原始光谱数据都是在Savitzky-Golay(SG)平滑处理后,使用PLS方法在主成分为4时预测效果较好。PLS模型在2-折交叉验证下,氧乐果在480~680nm波段,建模集相关系数Rc=0.977 0,均方根误差RMSEC=5.801,验证集相关系数Rp=0.963 0,均方根误差RMSEP=7.904;毒死蜱在460~850nm波段,Rc=0.997 0,RMSEC=2.281,Rp=0.984 7,RMSEP=3.170。该方法比色试剂配制简单安全,室温下比色反应时间为2min,满足快速、安全的检测要求,为进一步研究实用的农残检测仪器提供了新方法。
In order to detect the pesticide residues of omethoate and chlorpyrifos rapidly and safely, the absorption spectra of two pesticides were collected by the improved palladium chloride colorimetric method. Principal component analysis (PCA) and partial least squares (PLS) to establish a predictive model. The results showed that: 1) acetic acid instead of the traditional concentrated hydrochloric acid prepared palladium chloride colorimetric reagent is more ideal, the detection limit of the absorption spectrum of omethoate and chlorpyrifos can distinguish 0.05 and 0.50mg / L, basically meet GB 2763- 2014 Inspection requirements for some fruits and vegetables. 2) The sensitive wavelengths of absorption spectra of omethoate and chlorpyrifos were 510 and 499 nm, respectively, to determine the optimal modeling wavelength band. Comparing the modeling results of PCA and PLS methods, the original spectral data of the two pesticides are all smoothed by Savitzky-Golay (SG), and the PLS method is better when the principal component is 4. In the PLS model, with the 2-fold cross-validation, the correlation coefficient Rc = 0.977 0 and root mean square error RMSEC = 5.801 for Omethoate in the band of 480-680 nm, the validation set correlation coefficient Rp = 0.963 0, the root mean square error RMSEP = 7.904; chlorpyrifos in the 460-850 nm band, Rc = 0.997 0, RMSEC = 2.281, Rp = 0.984 7, RMSEP = 3.170. The method has the advantages of simple and safe preparation of the colorimetric reagent, and the colorimetric reaction time at room temperature for 2min, which meets the requirements of fast and safe detection and provides a new method for further research on practical pesticide detection instruments.