A spectrophotometric method for determination of fenoxaprop-p-ethyl herbicide using flow injection system has been proposed. The fenoxaprop-p-ethyl was converted into hydroxamic acid in the presence of hydroxylamine hydrochloride in alkaline media. The hydroxamic acid produced was further reacted with iron(III) to form red color tris iron hydroxamate complex. The absorbance of the complex was measured at 500 nm using flow injection system. The method shows a linear range between 1.0-20.0 µg mL-1 with molar absorptivity of 1.81 × 10(4) L mol-1 cm-1. The limit of detection and limit of quantification were calculated and found to be 0.29 ± 0.1 µg mL-1 and 0.96 ± 0.1 µg mL-1 respectively. Similarly the average limit of detection and limit of quantification were calculated for residue determination and were found 0.35 and 0.45 µg g-1 respectively for wheat grains and 1.2 and 1.5 µg g-1 respectively for barley grains. The sample through put was 90 samples h-1. The method was successfully applied to different grain samples.
fenoxaprop-p-ethyl; hydroxamic acid; iron(III); flow injection; spectrophotometric method
