Chiang Mai Journal of Science

Tildipirosin, a derivative of tylosin, is a semisynthetic 16-membered-ring macrolide antimicrobial. An ultra-performance hydrophilic interaction liquid chromatography-tandem high resolution quadrupole time-of-flight mass spectrometry method is reported herein to detect tildipirosin. Experiments were conducted to investigate the effects of the chromatographic column and the pH of the mobile phase on the separation of tildipirosin. Experimental results showed that the best detection conditions were as follows: a ACQUITY UPLC BEH Amide (100´2.1 mm, 1.7 mm) chromatographic column was used for the separation, with acetonitrile (containing 10 mmol/L ammonium formate, 0.125% formic acid, 5% water ) and 0.125% formic acid aqueous solution (containing 10 mmol/L ammonium formate) as the mobile phases. The flow rate was 0.4 mL/min and the temperature of the column was set at 40 °C. Electrospray ionization mass spectrometry (ESI-MS) was used as the detector, applied in the full scan positive ion mode. The linear detection range was 62.51000 ng/mL with a correlation coefficient of 0.9962. The limit of detection and quantitation were 0.74 and 2.45 ng/mL. The developed method exhibited good repeatability and high accuracy. The tildipirosin fragments were analyzed and compared using the Molecular Structure Correlator. The overall matching score was 98.99 and the matching scores of five main fragments were above 90, which provided the necessary evidence for the structural confirmation of tildipirosin.