A Fast and Sensitive LC/MS/MS Method for Quantitation of Fosfomycin in Human Plasma with HILIC Chromatography

Significance of the Topic

Fosfomycin is a broad-spectrum antibiotic experiencing renewed interest due to rising multidrug-resistant infections. Accurate measurement of its plasma concentrations is essential for pharmacokinetic studies and therapy optimization.

Objectives and Study Overview

This work aimed to establish a rapid and sensitive LC/MS/MS assay using hydrophilic interaction chromatography to quantify fosfomycin in human plasma over a wide concentration range, supporting clinical monitoring and research.

Methodology and Instrumentation

The protocol involved protein precipitation with acetonitrile/methanol (1:1, v/v) at a 1:4 plasma/solvent ratio, followed by centrifugation and filtration. Separation was achieved on a Shim-pack GIS HILIC column (150x3.0mm, 3μm) in isocratic mode (10% aqueous 5mM ammonium acetate, 90% acetonitrile) at 0.3mL/min and 40°C. A Shimadzu LCMS-8060 triple quadrupole equipped with heated ESI in negative mode was used. Key MRM transitions: fosfomycin 137.05→79.0 (quantifier) and 137.05→63.0/81.05 (qualifiers); internal standard fosfomycin-13C3 benzylamine salt 140.0→79.0. Calibration spanned 0.02–6.0ppm in solution (1–300ppm in plasma).

Main Results and Discussion

• Linearity: R²≥0.999 across eight calibration levels.
• LLOQ: 0.02ppm (solution) with S/N≥10 and RSD<8%.
• Precision: intra-run RSD 0.9–4.7% (area).
• Accuracy: QC samples within ±15% of nominal.
• Recovery: 60.7–81.2% (plasma 1) and 63.8–77.5% (plasma 2).
• Matrix effect: 52.2–74.8% (plasma 1) and 64.4–76.5% (plasma 2).
• Analysis time: approximately 3 minutes per injection.

Benefits and Practical Applications

The method delivers rapid throughput, high sensitivity, and robust quantitation suitable for pharmacokinetic profiling, therapeutic drug monitoring, and clinical research on fosfomycin.

Future Trends and Potential Applications

Advances may include coupling with ultra-high-performance LC for faster separations, automated micro-sampling for reduced volume requirements, and expanded application to other hydrophilic antibiotics and clinical biomarkers.

Conclusion

A fast, reliable, and sensitive HILIC LC/MS/MS assay was developed and validated for fosfomycin in human plasma, meeting key performance criteria for precision, accuracy, and recovery. This approach supports clinical and research needs.

Reference

1. Sun Zhe; Lee Jin Xing; Ong Cheryl; Xing Jie; Zhan Zhaoqi. A Fast and Sensitive LC/MS/MS Method for Quantitation of Fosfomycin in Human Plasma with HILIC Chromatography. ThP 757, Shimadzu Application Note.
2. Sime F.B.; Johnson A.; Whalley S.; Santoyo-Castelazo A.; Montgomery A.B.; Walters K.A.; Lipman J.; Hope W.W.; Roberts J.A. Antimicrob Agents Chemother. 2017;61(1):e01763-16.