Quantification of vancomycin in human serum by LC-MS/MS

Background: The aim of our work was to develop and validate a
reliable LC-MS/MS-based measurement procedure for the
quantification of vancomycin in serum, to be applied in the context
of efforts to standardize and harmonize therapeutic drug monitoring
of this compound using routine assays. Methods: Sample preparation
was based on protein precipitation followed by ultrafiltration. In
order to minimize differential modulation of ionization by matrix
constituents extended chromatographic separation was applied
leading to a retention time of 9.8 min for the analyte. Measurement
was done by HPLC-ESI-MS/MS. For internal standardization the
derivative vancomycin-glycin (ISTD) prepared by chemical synthesis
was used, HPLC conditions ensured coelution of ISTD with the
analyte. Results: In a bi-center validation total CVs of