Liquid Chromatographic Determination of Monensin in Premix and Animal Feeds: Collaborative Study

An interlaboratory study of a liquid chromatographic (LC) method for determining monensin in premix (60–80 g/lb or 132–5176 mg/g) and animal feeds (5–200 g/ton or 0.0055–0.22 mg/g) was conducted in laboratoriesin the United States, Canada, France, and Germany. The LC system used a reversed- phase column, postcolumn derivatization with vanillin, and UV detection. The method separates monensin from other ionophores such as narasin and salinomycin. Each laboratory analyzed a total of 20 samples of premix, liquid feed supplements, poultry, and cattle feeds. Concentrations of monensin in all samples ranged from 0 to 176 mg/g (80 g/lb). Reproducibility relative standard deviation (RSDR) for premix ranged from 2.8 to 3.4%. For feed samples containing monensin, repeatability standard deviation (Sr) ranged from 0.9 to 7.0. Reproducibility standard deviation (SR) ranged from 1.2 to 11. Repeatability relative standard deviation (RSDr) ranged from 6.1 to 21% and RSDR valuesranged from 8.6 to 25%. Sample preparation for the LC method is less labor intensive than that for the microbiological assays. The LC assay is more efficient than the microbiological assays. This LC method for determination of monensin in premix and animal feeds has been adopted first action by AOAC INTERNATIONAL.

Determination of Maduramicin in Feedingstuffs and Premixtures by Liquid Chromatography: Development, Validation, and Interlaboratory Study

A reversed-phase liquid chromatography method for determination of maduramicin in feedingstuffs and premixtures was developed, validated, and interlaboratory studied. The extraction solvent was methanol. Maduramicin was detected at 520 nm after postcolumn derivatization with vanillin.

Resonanz-Raman-Spektren von trans-Tetrahalogenodicarbonylosmaten(III) / Resonance Raman Spectra of trans-Tetrahalogenodicarbonylosmates(III)

The Raman spectra of (TBA)-trans[OsX4(CO)2] salts (X = Br, I; TBA+ = Tetrabutylammonium) show up to nine overtones and many combination tones of the totally symmetric stretching modes ν(OsX), ν(OsC) and ν(CO). The intensities of the overtones depend on the electronic spectra. The anharmonicity of the vibrations is small. All fundamentals are assigned by IR and Raman data.

Liquid chromatographic method for separation and determination of elaiophylin in biotechnology processes of salinomycin production

An LC method for the quick and precise quantitative determination of elaiophylin in biotechnology processes of salinomycin production was prepared. A mobile phase of methanol 0.04 M diammonium hydrogen phosphate pH 6.0-ethyl acetate (55:35:10, v/v/v) and an elevated column temperature optimized the chromatography. Separation of elaiophylin was obtained in 4-6 min. Positive identification and peak purity of elaiophylin have been carried out by photodiode array (PDA) detection. An agreement between the PDA spectra of samples and the elaiophylin standard were obtained.

Microbiological assay of avoparcin in animal feeds and pre-mixes--co-operative study

A microbiological method for the determination of the antibiotic growth promoter avoparcin in animal feeds and pre-mixes was first published in 1979. The existing method has been applied to new matrices as commercial use of avoparcin has spread. Problems with the existing analytical procedure have been reported, particularly in Germany. This paper identifies the causes of the problems and includes revisions to the existing analytical procedure. The testing of these revisions in co-operative studies with up to five German official laboratories is also reported.