Highly sensitive and simple fluorescence-based method for trace level residue determination of pinoxaden in agricultural and environmental samples: Experimental and DFT study

•The simple, fast and highly sensitive method for the determination of pinoxaden is based on fluorescence measurement of the Fe(III) based coordination complex of pinoxaden in the basic medium at 337 nm.•The signaling product is kinetically stable at room temperature having maximum fluorescence intensity with 0.2 µg mL−1 of Fe(III) at pH 9.•The complex shows a linear concentration range from 1 × 10−4,-1 × 10−3 µg mL−1 with a coefficient of determination R2 = 0.9917.•Density functional theory simulations shows stronger interaction energy (-1.11 eV) of Fe(III) ion with the pinoxaden.•The proposed approach is applied to quantify pinoxaden in the formulation and real agricultural and environmental samples and shows excellent recovery.