Assessment of the effect of non-ionic surfactant alkylphenol ethoxylates on the penetration of pesticides in fresh produce

Understanding the penetration behaviour of pesticide active ingredient (AI) in the presence of adjuvants is important in managing application efficacy and minimizing residues. This study investigates the impact of non-ionic surfactant alkylphenol ethoxylates (APEOs) on the penetration of two pesticides, systemic thiabendazole and non-systemic phosmet, in apple and spinach. Surface-enhanced Raman Spectroscopy (SERS) was employed using two different detection methods, namely XZ depth mapping and XY area mapping, in conjunction with liquid Chromatography with tandem mass spectrometry (LC-MS/MS) to investigate the penetration of various pesticide formulations over time. The SERS results showed that APEOs significantly increased the penetration depth of thiabendazole by 93.3 % in spinach and 21.4 % in apples, as well as enhanced the characteristic peak intensity by 73.52 % in spinach and 152.24 % in apples at the depth level of -60 µm after 3-day exposure. LC-MS/MS confirmed the consistent increases in internal thiabendazole residues in both fresh produce models due to APEOs. However, APEOs did not affect the penetration of the non-systemic phosmet in either apple or spinach. The combination of these two SERS mapping methods can provide a comprehensive understanding of the penetration profiles of different systemic pesticide formulations at various sensoria. This research advances the application of SERS mapping for studying the impact of nonionic surfactants on pesticide penetration which will aid the development of strategies to improve pesticide application efficiency and enhance food safety.