Residue uptake and depletion measurements of dietary oxadiazon in mammalian and avian species

Abstract

The herbicide oxadiazon, 2-(tert-butyl)-4-(2,4-dichloro-5-isopropyloxy-phenyl)-δ²-1, 3, 4-oxadiazoline 5-one, was fed in a total diet at three dosage levels to groups of dairy cows (0.5, 2.5, and 25 ppm) and to groups of male and laying female quail (20, 80, and 160 ppm) for 28 days. Control animals received basal diet rations. No residue (<5 ppb) was detected in milk or cream after three days withdrawal from fortified feed. The maximum plateau reached in milk was 83.8 ppb at the highest dosage fed. Tissues of cows sacrificed on the 12th day of withdrawal showed no residue (<20 ppb). Birds were sacrificed at weekly intervals during acclimation, intake, and withdrawal periods. Eggs were collected at the same intervals. Tissues were free of oxadiazon residue (<40 ppb) within two to seven days of returning the quail to the basal ration, and the eggs were residue-free within seven to fourteen days. The maximum residue found in adipose tissue of quail and their fresh eggs was 3100 ppb and 5400 ppb, respectively at the greatly exaggerated dosage of 160 ppm in the diet. A comprehensive analytical methodology, including liquid-liquid partition, absorption chomatography and electron-capture gas chromatography will be discussed.