Improving the selectivity and sensitivity for quantifying 8-α-hydroxy-mutilin in rabbit tissues by using basic mobile...

Area of Science:

• Analytical Chemistry
• Pharmacokinetics
• Veterinary Drug Residue Analysis

Background:

• Quantifying 8-α-hydroxy-mutilin, a tiamulin marker residue, in tissues is crucial for food safety.
• Previous LC-MS methods suffered from suboptimal selectivity and sensitivity due to pseudo MRM transitions.

Purpose of the Study:

• To develop and validate a highly sensitive and selective LC-MS/MS method for quantifying 8-α-hydroxy-mutilin in rabbit tissues.
• To establish a reliable analytical method for supporting residue depletion studies.

Main Methods:

• Utilized electrospray negative ionization in a basic medium to discover a true MRM transition (m/z 335→179).
• Developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method using pleuromutilin as an internal standard.
• Quantified 8-α-hydroxy-mutilin in rabbit muscle, liver, kidney, and fat tissues.

Main Results:

• A novel, highly selective and sensitive true MRM transition (m/z 335→179) was identified for 8-α-hydroxy-mutilin.
• The developed LC-MS/MS method demonstrated significant improvements in selectivity and sensitivity compared to previous methods.
• Validated method showed excellent accuracy (-5.0 to 3.1% bias) and precision (2.2 to 8.3% CV) within the 0.2-10 ppm range.

Conclusions:

• The novel LC-MS/MS method provides a robust and sensitive approach for quantifying tiamulin residue marker 8-α-hydroxy-mutilin in rabbit tissues.
• The validated method is suitable for supporting Good Laboratory Practice (GLP) tissue residue depletion studies.
• This advancement enhances the reliability of analytical data in veterinary drug residue analysis.