Quantification of teicoplanin in plasma by LC-MS with online sample clean-up and comparison with QMS assay.

Teicoplanin is a glycopeptide antibiotic used for the treatment of infections caused by Gram-positive bacteria. There is a good correlation between trough levels and clinical outcome, therefore therapeutic drug monitoring is recommended. Here we present a liquid chromatography-mass spectrometry (LC-MS) method with online extraction based on turbulent flow chromatography for the quantification of the five main components of teicoplanin, A2-1, A2-2, A2-3, A2-4, and A2-5. After online extraction, analytical chromatography was performed on a Hypersil Gold C8 column under acidic conditions. As mass spectrometer, a Q Exactive hybrid instrument was used. Samples were prepared by adding internal standard and subsequent centrifugation. Patient samples (n=125) that had previously been analyzed using a commercially available immunoassay (QMS teicoplanin) were re-analyzed by LC-MS. The imprecision was <6.9%, inaccuracy between 99.6% and 109%, for both, within- and between-day analysis. The method was shown to be free of matrix effects in the relevant time ranges and was compared to a commercially available immunoassay, QMS® teicoplanin from Thermo Fisher Scientific. The LC-MS assay produced comparable results to the QMS assay, the correlation coefficient was 0.856 (95% confidence interval 0.800-0.896). LC-MS yielded lower concentrations than the immunoassay as could be demonstrated by the bias of -1.16 mg/L (95% confidence interval -1.90-0.43 mg/L) in the Bland-Altman analysis. This specific, automated, LC-MS assay for teicoplanin is suitable for therapeutic drug monitoring.