Roland (1993) described a residue analytical method for bifenthrin and malathion in cereal grains. The method relied on hexane/acetone extraction followed by solvent evaporation and capillary GLC analysis. Electron-capture detection was used for bifenthrin and flame-photometric or thermionic detection for malathion. No specific information was available on the efficiency of extraction of aged bifenthrin residues from grain by hexane/acetone, but the fact that the bifenthrin residue levels on wheat at day 1 were unchanged by week 12 in the storage trials suggests that the solvent adequately extracted aged residues.
Measured recoveries of bifenthrin were in the range 94-101% from wheat fortified at 0.01, 0.25 and 0.50 mg/kg (Roland et al., 1995b) and 91-100% from wheat fortified at 0.1, 0.2, 0.3 and 0.4 mg/kg (Roland et al., 1995a). The data suggest an LOD of 0.01 mg/kg for bifenthrin on wheat.
Roland (1995) described a residue analytical method for bifenthrin and malathion in flour. The method relied on acetone extraction followed by solvent evaporation and clean-up by Florisil column chromatography. Bifenthrin and malathion were determined by capillary GLC, using an ECD for bifenthrin and an FPD for malathion. Bifenthrin recoveries with this method were 102, 103% from white flour at 0.05 mg/kg; 101, 102% from bran at 1.0 mg/kg; and 86, 95% from wholemeal bread at 0.2 mg/kg. The LOD was stated to be 0.01 mg/kg, but no recovery data were available below 0.05 mg/kg. No data were available for recoveries from white bread.
