Assisted distillation cleanup of pesticide residues in animal fats: new beadless distillation tube.
A new assisted distillation tube has been developed which contains no glass beads or glass wool. The sample is injected into the top of the tube, and a septum is not required. Large ground-glass joints (10/19) are used at the gas inlet and at the Florisil trap connection for maximum strength. Existing assisted distillation apparatus was easily modified to accept the new tubes. Recoveries of 9 organochlorine pesticides from butter and cattle fat ranged from 87 to 104% at a tube temperature of 230 degrees C and a nitrogen flow rate of 250 mL/min. No significant change occurred in recoveries of 8 of the 9 pesticides after 85 uses of the beadless tube. Only the recovery of HCB from butter decreased, from 95 to 80%, after 51 runs. The new tube was compared with the Unitrex glass bead-packed concentric tube at flow rates of 230, 400, and 600 mL nitrogen/min. Recoveries from the Unitrex tube were similar to those of the beadless tube for all pesticides except DDT which was significantly lower, indicating incomplete distillation at 250 mL/min and possible partial breakdown at 400 and 600 mL/min. A procedure is introduced for pressurized solvent washing of distillation tubes. This procedure is more efficient than vacuum washing.
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NSW Department of Agriculture, Board of Tick Control, Laboratory, Lismore, NSW, Australia.
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D000818:Animals; D002417:Cattle; D004041:Dietary Fats / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis*; D010573:Pesticide Residues / Q000032:analysis*; D013696:Temperature
D004041:Dietary Fats; D010573:Pesticide Residues