A detection method of mixed pesticide content on/in apples viaRaman spectrum

摘要

During the detection of pesticide residue via Raman spectral technology, it was easily to find that the characteristic peak intensity of one pesticide in mixture was lower than that of single pesticide solution with same concentration. Thus a correction method was urgently needed to be applied in Raman spectral detection. Chlopyrifos and acetamiprid pesticides, representatives of organophosphorus pesticides, were widely used on apples and leaf vegetables. In this study, the interaction between chlorpyrifos and acetamiprid in Raman spectroscopy detection was investigated with specialized equipment. Surface enhancement Raman spectroscopy (SERS) technology was effective in detecting pesticide residue with low concentration and used in the study. DuringRaman spectral detection, the characteristic peaks of chlopyrifos in 631cm'1 and the ones of pyrimidine in 634cm'1 and 1114cm'1, which were used for qualitative and quantitative discrimination of chlopyrifos and pyrimidine pesticides, all decreased obviously. In the study, Self-Modeling Mixture Analysis was applied for differentiating adjacent characteristic peaks. A series of samples which were covered with mixed chlopyrifos and pyrimidine pesticides residue both at the same concentration of 20g/kg, lOg/kg, 2.5g/kg, 0.1 g/kg, 0.01 g/kg and 0.001g/kg were prepared before the detection. Thorough comparing the characteristic peak intensity of chlopyrifos and pyrimidine pesticides and the mixture of them with same concentration, a correction method was put forward to make up for the loss by mixing. This correction method could correct the detection result of chlorpyrifos and acetamiprid mixture in the concentrations from 0.001 g/kg to 20g/kg. Then the correction method was applied on the detection results of apple samples with mixed chlopyrifos and acetamiprid pesticides at different concentrations. By correcting the intensity of the characteristic peaks, the final detection result was corrected. And then another group of apple samples of single chlopyrifos and acetamiprid pesticides at different concentrations were prepared to check the correction method. Thorough the comparison with detection results of samples with single and mixed pesticides, the result was acceptable and the correlation coefficient R2 was more than 0.9, which proves the reliability of the correction method. The correction method could be used in Pyrethrum pesticides residue in the next study. The research provided a new detection method in detecting mixing pesticides on agricultural products.