RESUMO
Objective: To establish a method for the determination of bilastine in human plasma, and evaluate the uncertainty by LC-MS/MS. Methods: The uncertainty sources were obtained from the whole process of the determination including repeatability, e-quipment error, weighting, solution preparation, calibration fitting and plasma sample handling. The uncertainty and synthesized un-certainty of each component were calculated, and then the expanded uncertainty was obtained. Results: The expanded uncertainty for low (15 ng·ml-1), medium (400 ng·ml-1) and high(1 200 ng·ml-1) level of bilastine was 1. 45 ng·ml-1, 28. 72 ng·ml-1 and 74. 61 ng·ml-1, respectively (k=2, P=95% ). Conclusion: The uncertainty in the determination of bilastine in human plasma is mainly caused by equipment error, solution preparation, protein precipitation and calibration fitting (especially at low level).