Biomedical subjects

C J Barnes

Publications and source records attributed to C J Barnes.

40 records · Page 3Linked to original sources

PubMedDate not supplied

Liquid chromatographic determination and gas chromatographic-mass spectrometric confirmation of lasalocid sodium in bovine liver: interlaboratory study.

An analytical method has been developed that can reliably measure the metabolic marker residue of lasalocid. The method monitors this marker residue in food samples to ensure that the total residue of toxicological concern is not being exceeded. Interlaboratory studies of the liquid chromatographic determinative procedure and the gas chromatographic/mass spectrometric confirmatory procedure for lasalocid sodium at the 0.7 ppm level and higher were successful.

Animals↗

PubMedDate not supplied

Liquid chromatographic determination of lasalocid sodium in chicken skin: interlaboratory study.

The U.S. Food and Drug Administration (FDA) sponsored an interlaboratory study of a liquid chromatographic determinative procedure for lasalocid sodium in chicken skin with adhering fat. Four laboratories analyzed 35 dosed tissue samples and 82 fortified tissue samples containing lasalocid at levels ranging from 0.1 to 0.6 ppm. Samples were homogenized with acetonitrile, washed with hexane, and partitioned into the mobile phase prior to analysis liquid chromatography with fluorescence detection. The results of the interlaboratory study showed good reproducibility for fortified samples. Fortification levels, average recoveries, and interlaboratory percent coefficients of variation were as follows: 0.6 ppm, 0.57 ppm, and 9.7; 0.3 ppm, 0.25 ppm, and 9.1; and 0.15 ppm, 0.14 ppm, and 7.0, respectively. Data for analysis of the dosed tissue also showed good agreement among the laboratories.

Adipose Tissue↗

PubMedDate not supplied

Determination of desaminosulfamethazine, sulfamethazine, and N4-acetylsulfamethazine by gas chromatography with electron capture detection and confirmation by gas chromatography-chemical ionization mass spectrometry.

An electron capture gas chromatographic method for the determination of sulfamethazine was modified to separate and quantitate simultaneously sulfamethazine and 2 of its metabolites, N4-acetylsulfamethazine and desaminosulfamethazine. The modified method was applied to incurred residues in a veal calf depletion study and to incurred residues in swine tissues. With capillary column gas chromatography-positive ion chemical ionization mass spectrometry, confirmation of the identities of incurred desaminosulfamethazine, N4-acetylsulfamethazine, and sulfamethazine in tissues was obtained from a single injection.

Animals↗

PubMedDate not supplied

Chlortetracycline, oxytetracycline, and tetracycline in edible animal tissues, liquid chromatographic method: collaborative study.

Thirteen laboratories analyzed samples of edible animal tissues for tetracycline residues. The method included extraction of analytes into buffer, elution from a C18 solid-phase extraction (SPE) cartridge, and reversed-phase liquid chromatographic (LC) analysis, including use of a confirmation column. An additional laboratory, using an alternative LC assay based on a different sample cleanup, also analyzed the samples. Results showed the 2 methods are comparable. The LC method for determination of cholortetracycline, oxytetracycline, and tetracycline in edible animal tissues has been adopted by AOAC INTERNATIONAL. Results from 13 laboratories indicate that the method under study provides generally better results at the higher concentrations tested than at concentrations near the detection limit and that there is less problem with interferences in muscle tissue than in kidney. The method can achieve reliable results for analytes and matrixes studied at concentrations from 0.1 to 0.6 ppm and above, depending on the analyte-matrix combination, with generally better performance to be expected with muscle than with kidney. The poorer performance for fortified samples, particularly kidney, was attributed to additional homogenization steps required to prepare these samples. Recovery of analytes from different lots of solid-phase extraction (SPE) cartridges was an important variable.

Animals↗