Dietary intake estimates as a means to the harmonization of maximum residue levels for veterinary drugs. II. Proposed application to the Free Trade Agreement between the United States and Canada.

The Free Trade Agreement between the United States and Canada (FTA) went into effect January 1, 1989. To implement certain provisions of the agreement on technical regulations and standards, the United States Food and Drug Administration's Center for Veterinary Medicine, Health and Welfare Canada's Bureau of Veterinary Drugs, and Agriculture Canada established the Working Group on Veterinary Drug Tolerances. The progress of the working group and its continuing efforts to harmonize tolerances for approximately 15 veterinary drugs are discussed.

High pressure liquid chromatographic determination of nitrofurazone and furazolidone in chicken and pork tissues.

A high pressure liquid chromatographic (HPLC) procedure is presented for the determination of nitrofurazone and furazolidone in chicken and pork tissues in the 2-40 ppb range. Muscle, liver, and kidney are homogenized with cold methanol and water (50 + 50). Following methanol evaporation, the nitrofurans are partitioned into ethyl acetate and cleaned up on an alumina column.

Determination of penicillin G, ampicillin, and cephapirin residues in tissues.

A cylinder plate microbiological method was developed for the rapid, quantitative determination of penicillin G, ampicillin, and cephapirin in animal tissues. The method uses agar plates seeded with stable spores of Bacillus stearothermophilus var. calidolactis and incubated 4 h at 64 degrees C.

Preparation and Immunological Properties of a Brilliant Blue-Protein Conjugate.

Brilliant Blue F.C.F.

Depletion of Brilliant Blue F.C.F., Penicillin G and Dihydrostreptomycin in Milk from Treated Cows with Experimentally Induced Mastitis.

A field trial was set up to compare depletion of Brilliant Blue F.C.F.

Microbiological determination of penicillin G, ampicillin, and cloxacillin residues in milk.

A fast cylinder plate microbiological method was developed for the quantitative determination of penicillin G, ampicillin, and cloxacillin in milk. Agar plates seeded with stable spores of Bacillus stearothermophilus var. calidolactis were used and incubated at 64 degrees C for 4 1/2 hr.

Isolation and identification of a fluorophore from ampicillin degradation.

A fluorescent impurity in ampicillin has been isolated and identified as 2-hydroxy-3-phenylpyrazine. The product is formed under acidic conditions similar to those employed in some fluorometric assay procedures. The mechanism of the reaction is proposed to involve cyclization by condensation of the penilloaldehyde of ampicillin.

Depletion of Brilliant Blue F.C.F. and Penicillin G in Milk from Treated Cows.

A field trial was set up to compare depletion of Brilliant Blue F.C.F.

High pressure liquid chromatographic determination of nitrofurazone in milk.

A rapid high pressure liquid chromatographic (HPLC) screening method for the quantitative determination of nitrofurazone in milk has been developed. The drug is extracted with ethyl acetate from a 2.0 ml milk serum sample, the organic layer is evaporated to dryness, and the residue is dissolved in the mobile phase and injected into the liquid chromatogarph.

Detection of Tracer Dyes in Milk.

An improved ion-exchange resin method to detect low levels of dye marker Brilliant Blue F.C.F.

Immunological properties of dialysis retentates from penicillin.

Retentates from benzylpenicillin preparations marketed in Canada were used in immunological studies in order to determine if they were immunogenic in experimental animals with respect to anaphylactic antibody production. The retentates obtained consisted mainly of penicillin polymers. Impurities of protein nature were either insignificant or absent.