Interlaboratory studies on two high-performance liquid chromatographic assays for tylosin (tartrate)

An interlaboratory study was performed on two high-performance liquid chromatographic methods to determine tylosin. The first method is a reversed-phase HPLC on a C-18 column, while the second is a method using a polymeric stationary phase. The first method is described in several pharmacopoeia monographs on tylosin, to determine the composition of a tylosin mixture, while the second method is recently proposed to determine both the composition and the contents in such a mixture. The interlaboratory studies were set-up and interpreted according to ISO guidelines. This paper is written as a tutorial type of article explaining the principles and methods of these guidelines. The results of both methods were compared. Both were found to have disadvantages but in general the old method is still preferred, both for composition determination and to assay the components. (C) 1999 Elsevier Science B.V. All rights reserved