Polarographic determination of robenidine residues in chicken tissues, eggs, litter, soil, and plant tissue.

Polarographic residue methods have been developed for determining robenidine (Robenz), 1,3-bis[p-chlorobenzylidene)amino]-guanidine monohydrochloride, in chicken tissues, eggs, litter, soil, and plants. The compound is extracted from chicken fat, skin, muscle, liver, and eggs with ethyl acetate; from blood with acetone; from plant tissue, litter, and kidney with acidic acetone; and from soil with basic methanol. After extraction by high-speed blending or overnight shaking, the extract is cleaned up by evaporation, solvent partition and/or elution from CG-50 ion exchange resin. Robenidine is quantitated by differential cathode ray polarography, using acidic aqueous methanol or acetic acid (1+1) supporting electrolyte. Recoveries ranged from 64 to 125% with an average overall recovery of 90%. The validated sensitivity is 0.1 ppm for chicken tissues, soil, and plants, 0.01 ppm for eggs, and 1 ppm for litter.

Gas-liquid chromatographic determination of levamisole residues in bovine milk.

A gas-liquid chromatographic (GLC) method is described for determining residues of levamisole, (1-)-(2,3,5,6-tetrahydro-6-phenylimidazo [2,1-b] thiazole), in milk. Levamisole is extracted from an alkaline milk sample with water-saturated ethyl acetate. After co-extractives are removed by various partitionings, the levamisole concentration is measured by GLC by using an alkali (RbSO4) flame ionization detector, vs. an external standard. This method is satisfactory for determining levamisole residues as low as 0.01 ppm in bovine milk. Apparent residues in control milk samples averaged less than 0.001 ppm. Recoveries of 0.01-2.0 ppm added levamisole ranged from 86.5 to 113%. Animals treated with various Tramisol formulations showed apparent levamisole residues below the validated sensitivity of the method (0.01 ppm) at sampling periods exceeding 48 hr.