Voltammetric study and electroanalytical determination of contraceptive levonorgestrel using silver solid amalgam electrode fabricated with nanoparticles

摘要

Here we describe the investigation of the electrochemical behaviour and the electroanalytical quantification of hormonal contraceptive levonorgestrel using solid amalgam electrode fabricated with silver nanoparticles. Until now, to the best of our knowledge, this is the first report of the use of solid working electrodes for levonorgestrel determination. Over this electrodic surface, the substance showed one cathodic peak at E-p = -1.41 V. Moreover, the electrochemical reduction of levonorgestrel was defined as an irreversible and mainly adsorption-controlled process involving two protons and two electrons. Square-wave adsorptive stripping voltammetry (SWAdSV) was used for the quantification of levonorgestrel. The instrumental and experimental parameters were studied and optimized. The best conditions of analysis were observed when using 0.04 mol L-1 Britton-Robinson (BR) buffer at pH 6.0. The analytical signal of levonorgestrel showed a linear dependence on the concentration range from 5.03 x 10(-7) mol L-1 to 1.01 x 10(-5) mol L-1. The LOD and LOQ obtained were 9.09 x 10(-8) mol L-1 and 3.03 x 10(-7) mol L-1, respectively. The voltammetric method was employed for the quantification of levonorgestrel in real pharmaceutical formulations and urine samples. The results provided good concordance with the expected values. It makes the working electrode used here an interesting and less toxic option for the analysis of reducible substances in comparison with the HMDE.