Persistence and bioaccumulation of oxyfluorfen residues in onion

A field study was conducted to determine persistence and bioaccumulation of oxyflorfen residues in onion crop at two growth stages. Oxyfluorfen (23.5% EC) was sprayed at 250 and 500 g ai/ha on the crop (variety, N53). Mature onion and soil samples were collected at harvest. Green onion were collected at 55 days from each treated and control plot and analyzed for oxyfluorfen residues by a validated high-performance liquid chromatography method with an accepted recovery of 78-92% at the minimum detectable concentration of 0.003 mu g g (-aEuro parts per thousand 1). Analysis showed 0.015 and 0.005 mu g g (-aEuro parts per thousand 1) residues of oxyfluorfen at 250 g a.i. ha (-aEuro parts per thousand 1) rate in green and mature onion samples, respectively; however, at 500 g a.i.ha (-aEuro parts per thousand 1) rates, 0.025 and 0.011 mu g g (-aEuro parts per thousand 1) of oxyfluorfen residues were detected in green and mature onion samples, respectively. Soil samples collected at harvest showed 0.003 and 0.003 mu g g (-aEuro parts per thousand 1) of oxyfluorfen residues at the doses 250 and 500 g a.i. ha (-aEuro parts per thousand 1), respectively. From the study, a pre-harvest interval of 118 days for onion crop after the herbicide application is suggested.