Determinação de 17β-estradiol com eletrodo grafite-ABS em sistema BIA com detecção amperométrica

Abstract

17β-estradiol (E2) is the main female sex hormone and is also used in pharmaceutical formulations (oral contraceptives and hormone replacement therapy). Because the body secretes this hormone and contaminates the aquatic environment, it is considered an important organic pollutant to monitor, due to its action on the human body as an endocrine disruptor. The development of rapid, sensitive, accurate, and portable methods is therefore of the utmost importance for its quantification “in situ” in different matrices. This work aimed to develop a methodology for the determination of E2 using a working electrode composed of a planar substrate printed with an insulating filament of acrylonitrile butadiene styrene (ABS) coated with a conductive composite of graphite and ABS (G/ABS). The initial electrochemical studies of E2 were investigated by cyclic voltammetry (CV) in a 0.04 mol L-1 Britton-Robinson (BR) buffer support electrolyte and 50.0 µmol L-1 analyte standard solution, in which irreversible behavior was observed with an anodic peak potential (Epa) of approximately +0.85 V. Subsequent studies were carried out in a batch injection analysis (BIA) system with amperometric detection (AD) under optimized conditions. Under these conditions, a calibration curve was constructed for different concentrations of E2, obtaining a sensitivity of 0.356 µA µmol-1 L and a linear range of 0.029 to 6.0 µmol L-1. The limit of detection (LOD) and limit of quantification (LOQ) were 0.009 µmol L-1 and 0.029 µmol L-1, respectively. The repeatability of the system was assessed for ten sequential injections of E2 at three concentration levels (0.5, 3.0, and 6.0 µmol L-1), and low coefficients variation were obtained (RSD = 8.6, 3.2, and 5.0%; n = 10, respectively). In addition, the reproducibility of the sensor preparation also showed a low deviation (PRD = 5.5%, n = 4), which confirms a reproducible manufacturing process. The methodology developed was applied to 4 different river water samples, obtaining concentrations ranging from 2.23 to 63.84 µmol L-1. For one of the water samples, 84, 89, and 129% recoveries were obtained for concentrations of 1.0, 3.0, and 5.0 µmol L-1, respectively. These results suggest that the G/ABS electrode in a BIA-AD system is promising for determining E2 in the samples evaluated.