Liquid chromatographic determination of RH-5992, an ecdysone agonist, in some forestry matrixes

A liquid chromatographic method is described for the analysis of RH-5992 (N'-t-butyl-N'-[3,5-dimethyl-benzoyl]-N- [-ethylbenzoyl]hydrazine) from various terrestrial and aquatic forestry matrixes and stream water. The processed soils, litter, oak foliage, sediment, aquatic plants, and fish were extracted with a mixture of acetone and water; balsam fir needles were extracted with acidified methanol solution; stream water was extracted with dichloromethane. Aliquots of crude extracts were solvent partitioned, concentrated, and cleaned up by using Florisil or Prepsep-NH2 columns. After fractional elution of the columns with hexane-ethyl acetate as the eluent, the eluates were analyzed on a liquid chromatograph equipped with a diode-array UV detector set at 236 nm, using an RP-8, 10 microns column with a mobile phase of acetonitrile-dioxane-water. Fir needles required methanol in addition to the 3 solvents in the mobile phase mixture. Water samples did not require any column cleanup. Mean recoveries for the analyte ranged from 84 to 98%, with coefficients of variation from 5 to 10%. Limits of detection (LOD) and limits of quantitation (LOQ) ranged from 0.004 to 0.030 ppm and from 0.013 to 0.101 ppm, respectively, for various forestry matrixes. LOD and LOQ for natural waters were 0.050 and 0.166 ppb, respectively.