Rodenticides, Problems Encountered in the Physicochemical Analysis of Warfarin

Abstract

Since the anticoagulant rodenticide, warfarin, was registered for general use (1950), commercial concentrates and finished baits have been assayed for warfarin content by physicochemical means.Concentrates and most finished baits presented no particular problem. However, two types of finished baits, one a coated grain and the other a pelletized grain mixture, yielded low results when assayed by the usual method employing a diethyl ether extraction. Substituting a weak alkaline solution for the diethyl ether allowed 90 to 100% recovery of warfarin in these baits. These findings were substantiated by biological assay. Anticoagulant rodenticides had their inception with the isolation, identification, and synthesis of the active principle in spoiled sweet clover hay, which causes a hemorrhagic condition in livestock, particularly cattle, frequently resulting in death (2,9,13). This factor was found to be 3,3 '-methylenebis (4hydroxvcoumarin), later designated as Dicumarol.