High Performance Liquid Chromato-Graphic Method For The Determination Of Permethrin Deposits In A Forestry Spray Trial

Abstract

A convenient and sensitive reversed-phase high performance liquid Chromatographie method has been developed for the determination of perraethrin [3-phenoxybenzyl (±)- cis,trans -3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropanecarboxylate] insecticide. Various isocratic and gradient mobile phases, consisting of acetonitrile:water (CH₃CN:H₂O) and methanol:water (CH₃OH:H₂O) solvent systems at two flow rates, were tested to separate and quantify the Isoners of permethrin using octadecylsilyl (ODS) (Regis 5μ m) and octylsilyl (OS) (RP-8, 10 μ m) bonded columns. The optimal mobile phase for perraethrin using the ODS column was 70:30 (v/v) CH₃CN:H₂O mixture at flow rates of either 1.0 or 1.5 mL/min. The measurement was done with a UV detector at 200 nm and 50°C. The OS column gave a less satisfactory separation than the ODS. Gradient elution systems examined did not improve the iso-meric separation of perraethrin. Using the method developed, deposit levels obtained on various sampling units during a perraethrin spray trial were analyzed after elution or extraction followed by necessary column cleanup. Minimum levels of detection for permethrin varied from 1 to 3 ng depending on the nature of the sampler used.