Abstract
Surface-enhanced Raman spectroscopy (SERS) is an emerging technique for the detection of pesticide residues on food surfaces, permitting quantitative measurement of pesticide residues without pretreating the sample. However, previous studies have mainly involved the single Raman spectrum of samples, while have given little information on pesticide residue distribution. In this paper, gold nanoparticles were used as surface enhancers to obtain the Raman spectra of omethoate and chlorpyrifos, using the Raman shifts of 413 cm−1 (omethoate) and 346 & 634 cm−1 (chlorpyrifos) as the peaks of interest. Different concentrations of pesticide solution were quantitatively analyzed and the regression curve model was established, whereby the solutions of omethoate and chlorpyrifos were used to study the distribution of pesticide residues on an apple surface by SERS microscopy imaging. Our study shows that this method can achieve rapid and quantitative detection and obtain basic information about the distribution of pesticide residues during pesticide application, which has the potential to be applied to the studies of the diffusion and absorption processes of pesticides in agricultural products.
Highlights
Omethoate and chlorpyrifos are efficient insecticides with a strong contact and stomach toxicity, and are widely used in the cultivation of fruits, vegetables and other crops
To eliminate the signal caused by the gold nanoparticles themselves, gold nanoparticles were dropped onto a clean apple surface and the Raman signal was measured (Fig. 2(e)), which does not exhibit characteristic Raman peaks
We used the SERS technique to obtain the Raman spectra of omethoate and chlorpyrifos
Summary
Omethoate and chlorpyrifos are efficient insecticides with a strong contact and stomach toxicity, and are widely used in the cultivation of fruits, vegetables and other crops. A er being applied to kill pests, a portion of the pesticides remains on the surface of the crop. This residue, coupled with overuse of the chemicals on the crops, can exert a certain degree of harm to the human body.[1,2,3] Fruit is necessary for people's daily life, so the detection of pesticide residues on the surface of the fruit is crucial. The surface-enhanced Raman spectroscopy (SERS) technique, detects the molecules adsorbed in the surface of roughened metal nanomaterials (gold, silver, copper and so on) to produce physical and chemical enhancements that increase the Raman signal intensity by 1010 to 1011 times.[11,12]
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