###### Abstract  
An electroanalytical study for possible simultaneous detection of three naturally occurring isomers of vitamin E (\(\alpha\), \(\gamma\), and \(\delta\)-tocopherol) was performed. This research includes several optimization steps, such as selection of electrode material, composition of working medium, selection of electrochemical technique, and parameters of square-wave voltammetry (SWV), to reach a well-defined recognition of peaks. A glassy carbon electrode, 99.9% acetonitrile containing 0.1 mol L\({}^{-1}\) lithium perchlorate, SWV at the potential step of 1 mV, potential amplitude of 25 mV, and frequency of 25 Hz were decided as the most suitable working conditions. Nevertheless, the corresponding anodic peaks were not sufficiently separated due to their overlapping. Thus, four standard evaluation methods (polynomial or linear baseline, zero base, and deconvolution) were compared, and the last-mentioned method was chosen as optimum. Similar linear ranges from 3.0 \(\times\) 10\({}^{-6}\) to 1.0 \(\times\) 10\({}^{-5}\) mol L\({}^{-1}\) were obtained for \(\alpha\), \(\gamma\), and 8-tocopherol, characterized by determination coefficient of 0.998, 0.985, and 0.994, quantification limits of 11.28, 2.70, and 3.67 \(\times\) 10\({}^{-6}\) mol L\({}^{-1}\) and detection limits of 3.72, 0.89, and 1.21 \(\times\) 10\({}^{-6}\) mol L\({}^{-1}\), respectively. A recovery from 72.0 to 128.5% for different concentration ratios of tocopherols has been achieved. This recovery range is in the accordance with values reported for liquid chromatography. evaluation methods; glassy carbon electrode; simultaneous detection; square wave voltammetry; tocopherols 20212021202120212021202120212021202120212021202-position responsible for their lipophilic properties [5; 15; 16]. Classification of \(\alpha\)-, \(\beta\)-, \(\gamma\)-, and \(\delta\)-forms of tocopherols is based on the degree of methylation. Common samples with natural origin are a mixture of these forms. It is worth mentioning that \(\beta\)-tocopherol presenting negligible content [17] is not analytically important, while pharmaceutical and cosmetic products are rich in \(\alpha\)-tocopherol (\(\alpha\)-TOH) and \(\alpha\)-tocopherol acetate (\(\alpha\)-TOAc) content. Generally, high-performance liquid chromatography (HPLC) coupled with ultraviolet or fluorescence detector is used as a standard analytical method for the analysis of tocopherols isomers [4; 18]. The sample preparation, including saponification with the presence of an antioxidant and subsequent extraction into an organic solvent can cause significant losses of vitamin E [19; 20; 12]. Hence, a voltammetric approach in the analysis of tocopherols is proposed as an interesting alternative due to easier sampling, less time-consuming analysis, and low operating costs [19]. As fat-soluble antioxidants (occurring in reduced forms), they are considered as electroactive compounds [21; 22], which can be anodically oxidized at various working electrodes (glassy carbon [23], platinum electrode [24], and glassy carbon paste electrode [12] in pure organic solvents or in their aqueous mixtures). Voltametric determination of VE in pure aqueous solution is possible to be performed after their adsorptive/extractive accumulation onto the surface of the working electrode (medium-exchange procedure) [12]. Several studies have been reported on the simultaneous voltammetric determination of tocopherols. In all cases, an overlapping of their corresponding anodic peaks was observed [21; 22; 23; 24; 25; 26]. In 1973, an initial electrochemical study of individual tocopherols was reported by [PERSON] and [PERSON] [25]. In 1992, a scientific group around [PERSON] began to deal with their simultaneous electrochemical detection [21]. Unfortunately, no improvement in their separation using voltammetric approach has been reached. Later, [PERSON] performed an analysis of tocopherols mixtures at platinum microelectrode using differential pulse voltammetry (DPV).