RESUMO
A simple, rapid and sensitive polarographic method is described for the determination of lansoprazole in a pure form, capsules and in urine. The proposed method is based on the measurement of the direct current [DC[t]] and the differential pulse polarographic [DPP] peak produced by lansoprazole in Britton-Robison buffer at pH 9, which give a well-defined cathodic wave. The current-concentration relationship was found to be rectilinear over the range 2-20 micro.g/ml and 0.1-2 [micro g/ml, in the direct current DCt and in the differential pulse polarography DPP modes, respectively, with a minimum detectability [S/N = 2] of 0.01 micro,g/ml [2.7 x 10[-8] M]. The number of electrons involved in the reduction process was established through comparison of the wave height of lansoprazole with that obtained for an equimolar solution of omeprazole. The proposed method was successfully applied to the determination of lansoprazole in commercial capsules adopting the DCt techniques. The results obtained were in accordance with those found using the reported spectroscopic method. The percentage recovery was 100.8 +/- 1.4%. Furthermore, the proposed method was applied for the determination of lansoprazole in urine adopting the DPP technique. The percentage recovery was 99.15 +/- 1.22%