Online solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry for fungicide translocation...

This study describes the development and validation of an online solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry (online SPE-LC-MS/MS) method for evaluating the translocation of fluxapyroxad, bixafen, pyraclostrobin, trifloxystrobin and prothioconazole (determined as prothioconazole-desthio) in soybean leaves following foliar application, either alone or combined with a copper-based fertilizer. The method was optimized and validated after comparison with the conventional QuEChERS approach, highlighting important methodological advancements such as reduced sample handling, lower analysis time, and partial integration of sample preparation with instrumental analysis. Validation results demonstrated significant matrix effects for all analytes, with ionization suppression ranging from -60 to -27%; however procedural standard calibration efficiently compensated for these effects, resulting in satisfactory trueness and precision. Limits of detection and quantification were ≤1 μg L^-1 and ≤5 μg L^-1, respectively, while calibration curves showed good linearity (r > 0.997). Mean recoveries ranged from 90 to 120%, with intra- and inter-day precision below 19 and 14%, respectively, in accordance with the SANTE guidelines. The method was successfully applied to greenhouse translocation experiments, revealing enhanced fungicide redistribution in treatments combined with copper-based fertilizer. The results highlight the analytical and operational advantages of automation in plant-tissue pesticide analysis.