Imibenconazole-debenzyl

Regulatory position The residue definition is for both imibenconazole and its primary metabolite (imibenconazole-debenzyl)... 

Plant samples are homogenized with sodium hydrogencarbonate aqueous solution to prevent decomposition of the analytes during homogenization. Imibenconazole and its primary metabolite, imibenconazole-debenzyl, are extracted from plan materials and soil with methanol. After evaporation of methanol from the extracts, the residues are extracted with dichloromethane from the residual aqueous solution. The dichloromethane phase is cleaned up on Florisil and Cig columns. Imibenconazole and imibenconazole-debenzyl are determined by gas chromatography/nitrogen-phosphorus detection (GC/NPD). 

Pass the solution derived from Section 6.2.1 through a Florisil cartridge (conditioned prior to use successively with 5 mL of acetone and lOmL of n-hexane), then elute interfering substances with 10 mL of n-hexane-acetone (19 1, v/v) and discard the eluate. Elute imibenconazole and imibenconazole-debenzyl with 25 mL of n-hexane-acetone (3 2, v/v). Collect the eluate in a 50-mL round-bottom flask and concentrate the eluate to dryness by rotary evaporation. Dissolve the residue in 5mL of acetonitrile-water (3 17, v/v). 

Fused-silica capillary column, OV-351, 0.53-mm i.d., 15-m length, film thickness 1.0- xm (for imibenconazole-debenzyl)... 

Quantitation is performed by the calibration technique. Construct fresh calibration curves with imibenconazole and imibenconazole-debenzyl standard solutions for each set of analyses. Inject 2 qL of each standard solution (equivalent to 0.04-2 ng of imibenconazole and imibenconazole-debenzyl) into the gas chromatograph. Plot the peak areas obtained versus amount of imibenconazole and imibenconazole-debenzyl injected. 

The recoveries from untreated control samples fortified with imibenconazole and imibenconazole-debenzyl at levels of 0.008-0.2 mg ranged from 84 to 110% and from 88 to 115%, respectively. The limits of detection of imibenconazole and imibenconazole-debenzyl were 0.004 mg kg for each compound. The limits of determination of imibenconazole and imibenconazole-debenzyl were 0.008 mg kg for each compound. 

The residues R (mgkg ) of imibenconazole and the metabolite imibenconazole-debenzyl (calculated as imibenconazole by conversion factor) are calculated from the following equations ... 

W = amount of imibenconazole or imibenconazole-debenzyl for V read from calibration curve (ng)... 

---