Development and validation of a RP-HPLC method for the multi-residue analysis of herbicides in complex pesticide formulations

A reverse-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for the simultaneous quantification of Penoxsulam (PNX), Cyhalofop-butyl (CYB), and 2,4-D Ethyl Ester (2,4-D) in commercial wettable powder (WP) formulations. Chromatographic separation was performed utilizing a C18 column (250 mm × 4.6 mm, 5 μm) at a temperature of 35 °C, employing an isocratic mobile phase composed of acetonitrile and 0.1% aqueous orthophosphoric acid at a ratio of 70:30 (v/v). The technique used a flow rate of 1.0 mL/min, UV detection at 220 nm, and an injection volume of 20 µL. The method was validated for linearity (R² >0.998), precision (%RSD < 2.5%), accuracy (96.9%–103.2%), limit of detection (LOD) (0.2–0.3 ng/mL), and limit of quantification (LOQ) (0.6–0.9 ng/mL). It demonstrated significant robustness, negligible matrix effects, and superior system fit. This technology is cost-effective, reliable, and ideal for routine quality control of multicomponent herbicide formulations in agrochemical manufacture.