Oxidative amperometric reverse phase HPLC determination of bifenazate (Floramite 50WS) residue in scented rose (Rosa bourboniana Desp.)

The method for detection and determination of bifenazate residue and percent transfer to rose water in Scented Rose, Rosa bourboniana Desp. was studied. The acaricide: Floramite 50WS (bifenazate-D2341, C₁₇H₂₀N₂O₃) was quantified by reverse phase HPLC, LaChrom-Merck equipped with L-3500A oxidative electrochemical detector and Lichrospher 100 (C18) 250-4 end capped (5 μm) column. Mobile phase, 55:45 v/v (5% acetonitrile/95% sodium acetate buffer 50 mM, pH 4): (acetonitrile + 0.5% acetic acid) was pumped at 1 ml/min. HPLC oven was set at 60^°C and detector at working potential of +0.40 V, noise filter 60 dB/OCT, time constant 5 sec and range out +10 nA. Calibration from serial dilutions of 1 mg/L working solution showed good linearity (0.99) and LOD (0.10 mg/L). Good recoveries in leaf, flower, rose water and soil (94.67–107.00%) were achieved. In field, the acaricide persisted for about 30 days on leaves, while in the soil, it persisted for 15 days only. Residue persisted in flowers only up to the 7^th day and was below detection limit by the 15^th day. Half life _{(single dose)} was calculated to be 5.23 days on the leaves.