HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF AZADIRACHTININ CONIFER AND DECIDUOUS FOLIAGE, FOREST SOILS, LEAF-LITTER AND STREAM WATER

A high performance liquid chromatographic (HPLC) method for the determ ination of azadirachtin (AZ-A) in conifer and deciduous foliage, fores t 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 ac etate, purified on a Florisil(R) mini-column, eluted with ethyl acetat e and analyzed using a reversed-phase C-18 column, with UV detection a t 210 nm and acetonitrile/water gradient system. Analysis of AZ-A in t he stream water required only the steps from dichloromethane extractio n onwards. Limits of detection were 0.2 mug/g for foliage and soil, 0. 25 mug/g for litter and 5.0 mug/L for water. Overall mean recoveries f rom terrestrial samples fortified with AZ-A at 0.50 pg/g to 10.0 mug/g and stream water at 10.0 mug/L to 200 mug/L were > 80% with good repr oducibility. The applicability of the method was demonstrated by study ing the recovery levels of AZ-A in samples fortified with standard Mar gosan-O.