Sun Tong, Zhang Zhuo-yong, Xiang Yu-hong, Zhu Ruo-hua
Guang Pu Xue Yu Guang Pu Fen Xi. 2016 Feb;36(2):541-4.
Determination of carbaryl in rice by using Fourier transform far-infrared (FT- Far-IR) and terahertz time-domain spectroscopy (THz-TDS) combined with chemometrics was studied and the spectral characteristics of carbaryl in terahertz region was investigated. Samples were prepared by mixing carbaryl at different amounts with rice powder, and then a 13 mm diameter, and about 1 mm thick pellet with polyethylene (PE) as matrix was compressed under the pressure of 5-7 tons. Terahertz time domain spectra of the pellets were measured at 0.5~1.5 THz, and the absorption spectra at 1.6. 3 THz were acquired with Fourier transform far-IR spectroscopy. The method of sample preparation is so simple that it does not need separation and enrichment. The absorption peaks in the frequency range of 1.8-6.3 THz have been found at 3.2 and 5.2 THz by Far-IR. There are several weak absorption peaks in the range of 0.5-1.5 THz by THz-TDS. These two kinds of characteristic absorption spectra were randomly divided into calibration set and prediction set by leave-N-out cross-validation, respectively. Finally, the partial least squares regression (PLSR) method was used to establish two quantitative analysis models. The root mean square error (RMSECV), the root mean square errors of prediction (RMSEP) and the correlation coefficient of the prediction are used as a basis for the model of performance evaluation. For the R,, a higher value is better; for the RMSEC and RMSEP, lower is better. The obtained results demonstrated that the predictive accuracy of. the two models with PLSR method were satisfactory. For the FT-Far-IR model, the correlation between actual and predicted values of prediction samples (Rv) was 0.99. The root mean square error of prediction set (RMSEP) was 0.008 6, and for calibration set (RMSECV) was 0.007 7. For the THz-TDS model, R. was 0. 98, RMSEP was 0.004 4, and RMSECV was 0.002 5. Results proved that the technology of FT-Far-IR and THz- TDS can be a feasible tool for quantitative determination of carbaryl in rice. This paper provides a new method for the quantitative determination pesticide in other grain samples.
研究了采用傅里叶变换远红外（FT - Far - IR）和太赫兹时域光谱（THz - TDS）结合化学计量学方法测定大米中甲萘威的含量，并研究了甲萘威在太赫兹区域的光谱特征。将不同含量的甲萘威与米粉混合制备样品，然后以聚乙烯（PE）为基质，在5 - 7吨压力下压制出直径为13毫米、厚度约为1毫米的薄片。在0.51.5太赫兹范围内测量薄片的太赫兹时域光谱，并利用傅里叶变换远红外光谱获得1.63太赫兹的吸收光谱。该样品制备方法非常简单，无需分离和富集。通过远红外光谱发现在1.8 - 6.3太赫兹频率范围内的吸收峰位于3.2和5.2太赫兹处。通过太赫兹时域光谱在0.5 - 1.5太赫兹范围内有几个弱吸收峰。将这两种特征吸收光谱分别通过留一法交叉验证随机划分为校正集和预测集。最后，采用偏最小二乘回归（PLSR）方法建立了两个定量分析模型。以均方根误差（RMSECV）、预测均方根误差（RMSEP）和预测相关系数作为模型性能评价的依据。对于相关系数，值越高越好；对于RMSEC和RMSEP，值越低越好。所得结果表明，采用PLSR方法的两个模型的预测精度令人满意。对于FT - Far - IR模型，预测样品实际值与预测值之间的相关性（Rv）为0.99。预测集的均方根误差（RMSEP）为(0.0086)，校正集的均方根误差（RMSECV）为(0.0077)。对于THz - TDS模型，Rv为0.98，RMSEP为(0.0044)，RMSECV为(0.0025)。结果证明，FT - Far - IR和THz - TDS技术可作为定量测定大米中甲萘威的可行工具。本文为定量测定其他谷物样品中的农药提供了一种新方法。
