Ultra performance liquid chromatography PDA method for determination of tigecycline in human plasma

: A simple ultra performance liquid chromatography with photodiode array method for the quantification of human plasma concentrations of tigecycline was developed and validated. Quinaxoline, used as an internal standard, was added to 500 μL of plasma before adding 1 mL of protein precipitation solution. The extracts were dried in a vacuum centrifuge system at 60°C and reconstituted with 60 μL of water and acetonitrile (95:5, vol/vol), and 5 μL was injected onto an ACQUITY UPLC H-Class system. Chromatographic separation was performed on a C18 ACQUITY UPLC HSS T3 column using a gradient of potassium phosphate buffer (pH 3.2) and acetonitrile. Detection was performed using a photodiode array detector at 350 nm. Relative error at 3 quality control concentrations ranged from -2.49% to -8.74%. Intraday and interday (percent relative standard error) precision ranged from 3.93% to 12.27% and from 9.53% to 13.32%, respectively. Limit of quantification and limit of detection were 0.024 and 0.006 μg/mL, respectively. Mean recovery was 95%. The calibration curve was linear up to 6 μg/mL. This concentration range proved to be adequate to measure tigecycline concentrations in patients treated with the drug, therefore this method would be suitable for therapeutic drug monitoring.