Comparison of Automatic and Manual Turbidimetric Analyses of Tylosin in Feeds with the Plate Method

Abstract

Two laboratories participated in a comparison of a manual turbidimetric assay with the AUTOTURB® System and the AOAC method of analysis of tylosin in 4 feed samples. Results showed no significant difference between the 2 turbidimetric assays. When the AOAC method was considered, the difference between laboratories was significant. On an overall basis the turbidimetric methods were significantly higher than the plate method. The relative standard deviation was higher (6.72%) for the plate assay versus turbidimetric assay (4.5%). The mean recovery in both laboratories was significantly less than the labeled amount of tylosin by all 3 methods.