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

An interlaboratory study was performed on two high-performance liquid chrom atographic methods to determine tylosin. The first method is a reversed-pha se HPLC on a C-18 column, while the second is a method using a polymeric st ationary phase. The first method is described in several pharmacopoeia mono graphs on tylosin, to determine the composition of a tylosin mixture, while the second method is recently proposed to determine both the composition a nd the contents in such a mixture. The interlaboratory studies were set-up and interpreted according to ISO guidelines. This paper is written as a tut orial type of article explaining the principles and methods of these guidel ines. The results of both methods were compared. Both were found to have di sadvantages but in general the old method is still preferred, both for comp osition determination and to assay the components. (C) 1999 Elsevier Scienc e B.V. All rights reserved.