Stability of Tylosin A in manure containing test systems determined by high performance liquid chromatography

Tylosin is a widely used antibiotic for the treatment of infections in swin e. Tylosin consists of a mixture of Tylosin A, Tylosin B, Tylosin C and Tyl osin D. All components contribute to the potency of tylosin but Tylosin A i s by far the major component (usually about 90% and not less than 80%). A f ast, robust and easily performed HPLC method has been developed for determi nation of Tylosin A in the presence of tylosin residues; Tylosin B, Tylosin C and Tylosin D in manure containing incubation media. The separation was performed using a YMC-Pack ODS-AQ column (250 x 4.6 mm i.d., 5 mu m particl e size) operated at 35 degrees C. The mobile phase consisted of 2.25% (w/v) sodium perchlorate pH 2.5-acetonitrile (60:40 v/v). Detection was performe d by measuring the UV absorption at a wavelength of 290 nm. Calibration cur ves of tylosin made in the incubation medium containing 6.4% manure were li near in the range from 0.375 to 128.0 mg/l (R-2 = 0.999). The limit of quan titation (at the RSD 20% level) for Tylosin A was found to be 0.4 mg/l in i ncubation media containing 6.4% manure. The recovery of Tylosin A was in th e range from 100% to 108% depending on the concentration of manure. The rep roducibility was good as the relative standard deviation (n = 4) in each ma trix tested was in the range from 0.7 to 1.9 at the 25 mg/l level. The stab ility of Tylosin A was studied under methanogenic conditions and the half-l ife was found to be less than two days. Studies under aerobic conditions sh owed that the degradation rate was found to increase with increasing concen trations of manure particles in the incubation medium. It is, however, not clear whether the decrease in the concentration of Tylosin A is caused by s orption, abiotic or biotic chemical degradation. The major degradation prod uct of Tylosin A in methanogenic as well as aerobic incubation media has a UV-spectrum and a retention time corresponding to Tylosin B. Furthermore, T ylosin D is believed to be a minor degradation product. (C) 2000 Elsevier S cience Ltd. All rights reserved.