High Performance Liquid Chromatographic Determination of Azadirachtin in Conifer and Deciduous Foliage, Forest Soils, Leaf Litter and Stream Water

Abstract

A high performance liquid chromatographic (HPLC) method for the determination of azadirachtin (AZ-A) in conifer and deciduous foliage, forest soil, litter and stream water is described. AZ-A was extracted from the solid matrices by aqueous methanol, concentrated, partitioned with hexane and re-extracted into dichloromethane layer. After evaporation of the dichloromethane layer, the residues were dissolved in ethyl acetate, purified on a Florisil^® mini-column, eluted with ethyl acetate and analyzed using a reversed-phase C-18 column, with UV detection at 210 nm and acetonitrile/water gradient system. Analysis of AZ-A in the stream water required only the steps from dichloromethane extraction onwards. Limits of detection were 0.2 μg/g for foliage and soil. 0.25 μg/g for litter and 5.0 μg/L for water. Overall mean recoveries from terrestrial samples fortified with AZ-A at 0.50 μg/g to 10.0 μg/g and stream water at 10.0 μg/L to 200 μg/L were > 80% with good reproducibility. The applicability of the method was demonstrated by studying the recover) levels of AZ-A in samples fortified with standard Margosan-O.