Direct injection LC–MS/MS method for the determination of teicoplanin in human plasma

•We developed a direct injection-based LC–MS/MS method to obtain teicoplanin in human plasma.•Only 20 μL of plasma was required for sample preparation.•Patient plasma samples were diluted in an aqueous buffer prior to injection into the LC–MS/MS system.•The method was fully validated and successfully applied to therapeutic drug monitoring (TDM) of teicoplanin in routine clinical practice.

A direct injection-based, simple, accurate, and robust LC–MS/MS method was developed and validated for the determination of teicoplanin in human plasma. Patient plasma samples were diluted in an aqueous buffer prior to injection into the LC–MS/MS system. Chromatographic separation was achieved using a Cadenza HS-C18 column and a gradient mixture of acetonitrile–water (both containing 0.1% formic acid) as the mobile phase at a flow rate of 0.5 mL/min. The analytes were detected in multiple reaction monitoring mode with positive ion electrospray ionization. The concentration of teicoplanin was determined as the sum of six components (A3-1, A2-1, A2-2, A2-3, A2-4, and A2-5). The calibration curve was linear over a concentration range of 1–50 mg/L, which covered the clinically accepted trough and therapeutic plasma levels. The intra- and inter-day precision and accuracy values were both less than 15%. This validated method was successfully applied to therapeutic drug monitoring of teicoplanin in routine clinical practice. Thus, we expect it to be useful for the determination of teicoplanin concentration in human plasma.