[Analytical Method for Tylosin in Livestock Products and Honey Using LC-MS/MS].

This study proposes a method to determine tylosin A in livestock products and tylosin A and B in honey using LC-MS/MS. The chilled samples were homogenized with a chilled mixture of ethanol and 20% (v/v) acetic acid (1 : 1, v/v),which were further cooled with ice until extraction was initiated. Acetone was used to extract analytes from the samples. These extracts were defatted using n-hexane (this step was omitted for honey) and purified with an octadecyl silylated silica gel cartridge column (Bond Elut C18).HPLC was performed on an Inertsil ODS-4 column using a gradient formed from 0.1% (v/v) formic acid in 5 mmol/L ammonium formate and 0.1% (v/v) formic acid in acetonitrile. Tylosin A and B were detected using tandem mass spectrometry with positive ion electrospray ionization. Recovery tests for tylosin A were performed in bovine muscle, fat, liver, milk, egg, and honey and those for tylosin B were performed in honey. The samples were fortified at the maximum residue limits for the analytes or at quantitative limits: 0.005 and 0.004 mg/kg for tylosin A and B, respectively. The trueness (n=5) of the analytes ranged from 83.1% to 94.9%, with the repeatability of from 0.7% to 7.1%.