Determination of leflunomide in pharmaceutical tablets by flow-injection analysis

Abstract

A flow injection analysis (FIA) of leflunomide using UV-detection is described, in this study. The most suitable carrier solvent was found to be an aqueous solution of ethanol (25%, v/v). Leflunomide was determined at the optimum conditions, such as flow rate of 0.8 mL(.)min(-1) and detection wavelength of 260 nm. The method has been validated and linearity was examined in the range of 2.75 x 10(-6) - 1.10 X 10(-4) M. The limit of detection (LOD) and quantitation (LOQ) were calculated to be 2.60 x 10(-7) M (S/N = 3.3) and 7.87 x 10(-7) M (S/N = 10), respectively. The application of the proposed method has been performed in pharmaceutical tablets of leflunomide and excellent results were obtained. The results were compared with those obtained from UV-spectrophotometry. Insignificant difference was found between the methods. As a result, the FIA method for the determination of leflunomide in pharmaceutical tablets can be proposed as a precise, accurate, sensitive, and cheap method for routine analysis laboratories.