Introduction: In the present study, a sensitive and selective liquid chromatographytandem
mass spectrometry (LC-MS/MS) method was described for the determination of ceftiofur
(CEF) in cow milk and pharmaceutical preparations. CEF is an antibiotic compound, which is
commonly used in the treatment of animal diseases such as respiratory system, soft tissue, and foot
infections, as well as postpartum acute puerperal metritis. One of the critical features of CEF is its
prescription while breastfeeding cows; in accordance, its quantitative estimation is essential to
assess its residual amounts.
Methods: In the method reported herein, after simple protein precipitation using acetonitrile, the
pre-treated samples were introduced into an LC-MS/MS instrument equipped with a Chromolith®
High-Resolution RP-18 series HPLC column (100 mm × 4.6 mm from Merck KGaA, Germany).
Electrospray ionization was employed as the ionization source in the triple-quadrupole tandem
Results: For the calibration method using solvent-based standards, LOQ was 3.038 ng/mL, 12.15
ng/mL, and LOD was 1.215 ng/mL and 6.076 ng/mL for ESI+ and ESI- modes, respectively. On
the other hand, for the method of matrix-matched standards, LOQ was 1.701 ng/mL, 10.13 ng/mL,
and LOD was 0.486 ng/mL and 5.929 ng/mL for ESI+ and ESI- modes, respectively as obtained
from signal to noise ratio.
Conclusion: Applicability of both positive and negative ion modes was tested, and the analyte was
detected via multiple reaction monitoring. The distorting effects of the milk matrix on the MS
ionization and quantitation of CEF were overcome by using matrix-matched calibration for the first