Abstract
The use of pesticides will have an impact on food, organisms, and environment. Specifically, pesticide residues in food will damage human health. Because of its high permeability, low energy, high spectral resolution, and fingerprint characteristics, terahertz frequency-domain spectroscopy has been introduced into the determination of pesticides (imidacloprid, acetamiprid, and triadimefon) residues in food samples (glutinous rice flour, wheat flour, and corn flour) in our present study. These three pesticides exhibit their own absorption peaks in the region of 0.4–1.7 THz. For understanding the origins of these peaks, the experimental data are interpreted by using density functional theory calculations at the level of B3LYP/6-31G (d). It is found that these absorption peaks come from the intramolecular and intermolecular interactions. The absorption peaks of pesticides are still detectable in a mixture of pesticides and food samples when they reach a certain concentration. The results from chemometrics analysis show that quantitative detection of pesticides in food samples is feasible. The partial least squares regression models have high correlation coefficient (>0.99), low root-mean-square error of calibration (<1.5%), low root-mean-square error of cross-validation (<2.4%), and low root-mean-square error of prediction (<2.3%), indicating good quality of prediction for pesticides concentration. Our results prove that the terahertz frequency-domain spectrum combined with chemometrics can be used for the detection of pesticides in food samples.
Highlights
Imidacloprid, acetamiprid, and triadimefon, as common pesticides, are widely used in crop pest control and disease resistance
A new method based on THz frequency-domain spectroscopy (THz-FDS) combined with chemometrics is developed for the detection of imidacloprid, acetamiprid, and triadimefon in food samples
By comparing the experimental results and density functional theory (DFT) calculations, it is verified that the absorption peaks of these pesticides come from intramolecular and intermolecular interaction
Summary
Imidacloprid, acetamiprid, and triadimefon, as common pesticides, are widely used in crop pest control and disease resistance. The irrational utilization of these pesticides can lead to unsafe residue levels in agricultural products, which will have potential harm for human health. Pesticide residues in agricultural products are considered to be a huge health risk. Maximal residue limits of pesticides are established for different matrices by different countries. In the USA, the maximal residue limit of imidacloprid in wheat flour is 0.05 ppm [1]. In China, the maximal residue limit of imidacloprid is 0.05 ppm, while the maximal residue limits of acetamiprid and triadimefon are both 0.5 ppm [2]. The abusing of pesticides is becoming a serious problem despite the legal restrictions
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