Thiacloprid suspension formula optimization by a response surface methodology

A model thiacloprid 25% suspension concentrate was prepared using Tersperse2700 (X-1), AE1601 (X-2), xanthan gum (X-3) and Veegum (X-4). A response surface methodology (RSM) was used to evaluate the influences of four experimental factors on the aqueous separation ratio (R-1), centrifugal sedimentation ratio (R-2) and viscosity (R-3). The results show that the main factors influencing the three responses were X-3, X-4 and X-2 followed by X-1; moreover, several interactions were also significant. Multiple-response optimization was performed based on a desirability function, considering the minimum R-1, R-2, and R-3 as well as the financial cost. The integrated optimum conditions were X-3 = 0.24%, X-4 = 1.33%, X-2 = 0.50%, and X-1 = 2.90% (mass fraction). A verification experiment demonstrated that the optimized formula R-1, R-2, and R-3 were 1.69%, 2.63% and 257.74 mPa s with the average relative predicted value errors 7.69%, 4.18% and -1.41%, respectively. The response surface methodology is an effective approach for optimizing the suspension concentrate formula with comprehensive advantages.