Formulation optimization of prothioconazole + picoxystrobin 30% SC via multi-index weighted scoring method in combination with response surface methodology

The development of pesticide suspension concentrate (SC) formulation has long been hindered by unclear processes, inconsistent development methodologies, and the difficulty in resolving interactions among adjuvants. In this study, a systematic optimization of prothioconazole + picoxystrobin 30% SC formulation was conducted by combining analytic hierarchy process (AHP), single-factor experiments, and Box-Behnken design response surface methodology (RSM). The results showed that the consistency ratio (CR) of the AHP judgment matrix was 0.062 (< 0.1), confirming reasonable judgment logic, and the obtained weight coefficients of the criterion layer were suitable for constructing a weighted scoring system. Based on the weighted scores from single-factor tests, the appropriate levels of adjuvants 3016 and 505 (2% each) and the thickeners AF-10 (1%) and xanthan gum (0.125%) were preliminarily identified. These levels were then used to set the factor levels and ranges for the Box-Behnken design. The coefficient of determination (R²) of the model was 0.9680, indicating that the model could explain 96.80% of the variation in the response and exhibited a high degree of fit. The optimized formulation was determined as: prothioconazole (20%), picoxystrobin(10%), 3016 adjuvant 1%, 505 adjuvant 1%, xanthan gum 0.125%, AF-10 1.5%, ethylene glycol 4.0%, defoamer 0.2%, preservative 0.1%, and deionized water to 100%. Under these conditions, the comprehensive weighted score of the formulation reached 53.40, which was in excellent agreement with the predicted value of 54.65 from the RSM model, giving a relative deviation of only 2.29%. These results demonstrate that the multi-index comprehensive weighted scoring method combined with Box-Behnken design response surface methodology can effectively optimize SC formulation systems, substantially enhance the stability and reproducibility of the preparation process, and provide a valuable reference for the development of pesticide suspension concentrates.