# Simultaneous determination of lincomycin, spiramycin, tylosin and tiamulin in animal feed using liquid chromatography coupled to mass spectrometry after a microbial assay

## TL;DR

This paper presents a reliable method to detect four antibiotics in animal feed using a microbial assay followed by liquid chromatography and mass spectrometry.

## Contribution

A validated method for simultaneous determination of four antibiotics in feed using microbial and chromatographic techniques.

## Key findings

- The method achieved satisfactory recoveries (86.6–105.1%) and acceptable repeatability and reproducibility.
- Limits of detection and quantification were within the range of 0.029–0.223 mg kg−1 depending on the antibiotic.
- The method meets EU requirements and is suitable for feed-safety control.

## Abstract

To monitor the occurrence of antibiotics in feed, a two-step control strategy is often adopted of screening by microbiological inhibition followed by confirmation by chromatographic techniques. This study is devoted to the development of a reliable method for simultaneous determination of lincomycin, spiramycin, tylosin and tiamulin in animal feed using liquid chromatography coupled to mass spectrometry after a microbial assay.

The analytes were extracted from feed using a methanol:water mixture, and solid-phase extraction was employed for the isolation of the antibiotics. The determination of the presence of lincomycin, spiramycin, tylosin and tiamulin was carried out using high-performance liquid chromatography with mass spectrometry.

The method was validated according to EU requirements. The decision limit and detection capability were 0.213–0.318 and 0.259–0.535 mg kg−1, respectively, and the limits of detection and quantification were 0.029–0.151 and 0.069–0.223 mg kg−1, respectively, depending on the analyte. Recoveries were satisfactory (86.6–105.1%), repeatability ranged from 2.6 to 18.3% and reproducibility from 6.2 to 11.7%.

The proposed method is reliable and applicable to identify four antibiotics for feed-safety control.