MSACL 2025 Abstract

Development and Validation of a Sensitive UPLC-QToF Method for Vancomycin, Ceftazidime, and Ceftriaxone in Cerebrospinal Fluid and Serum

Chao Sun, PhD, Yi Xiao, Zara Jalali, Edward Leung
University of Southern California Children's Hospital Los Angeles, Los Angeles, CA

Chao Sun, PhD (Presenter) University of Southern California, Children's Hospital of Los Angeles >> POSTER (PDF)

Presenter Bio: Dr. Chao Sun is a Clinical Chemistry Fellow at the University of Southern California, with a strong focus on the clinical application of mass spectrometry to improve patient care. He earned his PhD from The Ohio State University, where his research involved MS-based proteomics of mouse brain tissue following traumatic brain injury.

Dr. Sun has developed and implemented LC-MS/MS assays for therapeutic drug monitoring and clinical research, including:

CSF antibiotic quantification to support PK/PD studies and inform treatment guidelines for critically ill pediatric patients (in collaboration with Infectious Diseases).

Debrisoquine metabolism assays to evaluate tissue-engineered liver function models (with Surgery).

Busulfan, azoles, homocysteine, and MMA quantification, including method optimization and troubleshooting.

Urine organic acid analysis using UPLC-QToF in collaboration with the University of Michigan’s Medical Genetics team.

He also contributed to MALDI-ToF mass spectra analysis for drug resistance profiling in collaboration with Microbiology at USC Keck Medical Center.

Dr. Sun combines deep technical expertise with a collaborative clinical mindset, working directly with providers to interpret LC-MS/MS results, guide test utilization, and develop novel diagnostic approaches. He is committed to advancing mass spectrometry as a cornerstone of modern laboratory medicine and personalized healthcare.

Relevant Financial Disclosures (within past 24 months, reported on Jul 09, 2025) No relevant financial relationship(s) to disclose. Conflict mitigation NOT REQUIRED.

INTRODUCTION:
Vancomycin, ceftazidime, and ceftriaxone are antibiotics commonly used to treat central nervous system infections. We developed a sensitive liquid chromatography- quadrupole Time-of-Flight (UPLC-QToF) method that simultaneously measures these antibiotics in cerebrospinal fluid (CSF) and serum. This method will be used to analyze specimens to study the pharmacokinetics and blood-brain barrier penetration of these antibiotics. Additionally, it will aid in dosage optimization to minimize toxicity while maximizing therapeutic efficacy for patients with central nervous system infections.

METHODS:
CSF or serum was mixed with isotope-labeled internal standards and extracted using a 96-well Strata-X-C (Phenomenex) solid-phase extraction plate. The dried eluate was reconstituted with 75 µL of solvent and analyzed using a Xevo G3 QToF mass spectrometer (Waters) with an ACQUITY™ BEH C18 (1.7 µm, 2.1 × 50 mm) column (Waters). Accuracy was assessed using spike-recovery studies with CSF or synthetic serum. The analytical measurement range (AMR) was determined by spiking antibiotics into CSF or synthetic serum to generate seven specimens with increasing concentrations. Precision (repeatability and reproducibility) was assessed using quality control materials. Matrix effect was evaluated by comparing post-spiked extracted samples with neat antibiotic solutions (without solid-phase extraction).

RESULTS:
Linear regression was used to build the calibration curve. In both CSF and serum, the method demonstrated linearity for all antibiotics over a range of 0.1–10 µg/mL, with r² > 0.99. Repeatability and reproducibility were <10% CV. Minimum carryover was observed for both CSF and serum samples. Spike-recovery studies demonstrated recoveries of 89%–119% in serum samples and 91%–105% in CSF samples. Minimal matrix effect was observed in both serum and CSF samples.

CONCLUSION:
We have developed and validated a sensitive and rapid LC-QToF method for the simultaneous measurement of vancomycin, ceftazidime, and ceftriaxone in both serum and CSF.