Determination of terminal residues of oxyfluorfen in onion

Terminal residues of oxyfluorfen applied in direct seeded onion crop were analyzed in green onion, dry onion bulbs and soil samples under field condition. Oxyfluorfen was applied as early postemergence at 150, 200, 250 and 300 g ai ha⁻¹ in rabi, 2005 in onion field at Jabalpur. Representative onion samples treated with oxyfluorfen were collected at 90 days (green onion) and at 130 days (mature onion bulbs) after oxyfluorfen application and were analyzed by HPLC with diode array detector for residues. The residue level of oxyfluorfen in soil, green onion and mature onion bulbs was found 0.0015 μg g⁻¹ at 300 g/ha application rate and residues were below the detection limit at 150–250 g ha⁻¹ rates. The concentration of oxyfluorfen in the green onion and mature onion bulbs was 0.041, 0.041, 0.040 and 0.063 and 0.0034, 0.0035, 0.0050, 0.0460 μg g⁻¹ at 150–300 ha⁻¹ rates, respectively. Residues of oxyfluorfen applied in onion were below the maximum residue limit (0.05 μg g⁻¹).