Volume 24, Issue 3 (May 1996)
The Extraction and Determination of Azadirachtin from Soil and Insects by Supercritical Fluid Extraction
Azadirachtin is a powerful anti-feedant and insect growth-disrupting compound. A primary problem with the utilization of classical extraction techniques for determining azadirachtin is the high hydrophilicity of the compound. Further, since determination by high-performance liquid chromatography (HPLC) requires measuring absorbance at 214 nm, use of methanol for extraction requires a solvent exchange since methanol absorbs in this region. This paper demonstrates the use of supercritical fluid extraction for determination of azadirachtin residues. Methanol-modified supercritical carbon dioxide is used to extract azadirachtin from soil and Japanese beetle adult and larval forms. Greater than 80% of fortified material was recovered at spike concentrations of 1 to 2 µg/g. Using this procedure azadirachtin was determined to be field stable for less than 3 months. Azadirachtin was also successfully extracted from insects showing recovery levels of 75% and greater. The inability of modified supercritical carbon dioxide to cross the insect cuticle was also demonstrated.