Validation of a liquid chromatography-tandem mass spectrometry method for the simultaneous determination of sulfonamides, trimethoprim and dapsone in muscle, egg, milk and honey

ABSTRACT

A quantitative multi-residue method that includes 13 sulfonamides, trimethoprim and dapsone was developed and validated according to Commission Decision 2002/657/EC for muscle, milk egg and honey samples. For all matrices, the same extraction procedure was used. Samples were extracted with an acetone/dichloromethane mixture and cleaned up on aromatic sulfonic acid (SO₃H) SPE cartridges. After elution and concentration steps, analytes were identified and quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Data were acquired according to the multiple reaction-monitoring approach (MRM) and analytes were quantified both by the isotope dilution and the matrix-matched approaches calculating the response factors for the scanned product ions. The developed method shows good linearity, specificity, precision (repeatability and within-laboratory reproducibility), and trueness. Estimated CCβ for sulfonamides ranged between 5.6 and 8.2 µg kg⁻¹ for eggs, between 11.1 and 69.9 µg kg⁻¹ for milk, between 64.7 and 87.9 µg kg⁻¹ for muscle, and between 2.7 and 5.3 µg kg⁻¹ for honey. CCβ values for dapsone were 3.1, 0.6, 0.7 and 1.5 µg kg⁻¹ and for trimethoprim were 3.1, 6.7, 81.7 and 3.0 µg kg⁻¹ calculated for eggs, milk, muscle and honey, respectively. Recovery for all matrices was in the range from 89.1% and 109.7%. In matrix effect testing, no significant deviations were found between different samples of muscle and milk; however, a matrix effect was observed when testing different types of honey. The validation results demonstrate that the method is suitable for routine veterinary drug analysis and confirmation of suspect samples.

KEYWORDS:

• Sulfonamides
• trimethoprim
• dapsone
• validation
• various matrices
• liquid chromatography mass spectrometry

Acknowledgement

Development of the method presented in this paper would not have been possible without financial support and encouragement from the Croatian Veterinary Institute.

Disclosure statement

No potential conflict of interest was reported by the authors.