A selective 19F NMR spectroscopic method for determination of insecticide diflubenzuron in different media

A selective and rapid 19F NMR spectroscopic analytical procedure for insect growth regulator diflubenzuron, a phenylurea insecticide, has been developed. Optimal NMR sensitivity based upon T1 relaxation time was investigated for diflubenzuron and 4-fluorobenzoic acid as internal standard in dimethyl sulphoxide. The method was validated through spike and recovery for diflubenzuron from apple juice and its commercial sample (Dimilin) without any interference, separation steps and lengthy instrument time. The calibration curve was linear for diflubenzuron over the range of 25–1000 μg/ml, with detection limit (S/N = 3) of 6 μg/ml. The within- and between-day repeatability coefficients of variation were lower than 6 (n = 3) and 7 (n = 5), respectively. Recovery of diflubenzuron from spiked apple juice samples at two fortification levels were 96% and 92% with relative standard deviation of <10% (n = 3).