Smartphone-based rapid and low-cost method for the determination of eugenol content of clove essential oil. Ciência Rural, v.53, n.10, 2023. 1 Smartphone-based rapid and low-cost method for the determination of eugenol content of clove essential oil Método rápido e de baixo custo empregando smartphone para a determinação de eugenol em óleo essencial de cravo Izaura Ceolin dos Santos 1,2 Sandra Kunde Schlesner 1 Débora Piovesan de Moraes 1 Daniele de Freitas Fereira 1 Mônica Voss 1 Sandro Rogério Giacomelli 2 Juliano Smanioto Barin 1* ISSNe 1678-4596 Ciência Rural, Santa Maria, v.53:10, e20220498, 2023 Received 09.07.22 Approved 11.29.22 Returned by the author 02.14.23 CR-2022-0498.R1 Editor: Rudi Weiblen http://doi.org/10.1590/0103-8478cr20220498 INTRODUCTION Clove (Syzygium aromaticum, L.) is used since antiquity as a condiment and favoring, as well as for the elaboration of perfumes and aromatic incenses. Eugenol is the main component of clove essential oil, but β-caryophyllene and smaller amounts of other components can be found. It is a phenolic compound that has been suggested as a substitute for synthetic additives due to its antioxidant and antimicrobial characteristics (CHAIEB et al., 2007). The determination of eugenol content in clove essential oil is usually performed by gas chromatography (GC), a very selective technique widely used in laboratories (CHAIEB et al., 2007). However, GC is time-consuming, requires specifc knowledge for operation, and presents a high cost and a dedicated laboratory structure, which impairs its use for analysis in the feld (NADEEM et al., 2022). The search for the portability of analytical methods has been increased to allow simple and fast analysis using low-cost devices that the analyst 1 Departamento de Tecnologia e Ciência dos Alimentos, Universidade Federal de Santa Maria (UFSM), 97105-900, Santa Maria, RS, Brasil. E-mail: juliano@ufsm.br. * Corresponding author. 2 Departamento de Ciências Exatas e da Terra, Universidade Regional Integrada do Alto Uruguai e Missões (URI), Frederico Westphalen, RS, Brasil. ABSTRACT: The determination of eugenol in clove essential oil was performed using a smartphone-operated device, which was used for image capture and processing. The colorimetric reaction with the Folin-Ciocalteu reagent was used, and the lighting conditions were evaluated to capture images directly in 2 mL disposable vessels. The free application PhotoMetrix UVC was used for partial least squares regression calibration with suitable values (R² greater than 0.99). The accuracy of the proposed method was compared with traditional methods, such as gas chromatography (GC) and spectrophotometry, and it can be observed that there were no signifcant diferences (Student’s t-test (P > 0.05), with agreements from 97% to 101%. The smartphone method allowed the evaluation of several samples in a few minutes, with simple analysis steps and easy interpretation of the results. The miniaturized scale allowed the use of small amounts of reagents with minimal waste generation. Therefore, the proposed method can be easily operated in the feld and allows the evaluation of the quality of clove essential oil in places of restricted access without the need for a laboratory structure and specialized analysts. Key words: smartphone, clove, eugenol, digital images. RESUMO: A determinação de eugenol em óleo essencial de cravo-da-índia foi realizada utilizando um dispositivo operado com smartphone para captura e processamento de imagens. Para tal desenvolvimento foi utilizada a reação colorimétrica com o reagente de Folin-Ciocalteu. Foram avaliadas diferentes condições de iluminação para a captura das imagens diretamente em frascos descartáveis de 2 mL. O aplicativo livre PhotoMetrix UVC foi usado para a calibração por regressão de mínimos quadrados parciais com valores adequados (R 2 maior que 0.99). A exatidão do método proposto foi comparada com métodos tradicionais, tais como cromatografa gasosa (CG) e espectrofotometria, sem diferenças signifcativas (teste t de Student (P> 0,05) e com concordâncias entre 97% e 101%. O método com smartphone permitiu a avaliação de várias amostras em poucos minutos, com etapas de análise simples e com fácil interpretação dos resultados. A escala miniaturizada permitiu o uso de pequenas quantidades de reagentes e mínima geração de resíduos. Portanto, o método proposto pode ser facilmente operado em campo e permite avaliar a qualidade de óleo essencial de cravo- da- índia em locais de acesso restrito, sem a necessidade de estrutura laboratorial e analistas especializados. Palavras-chave: smartphone, cravo-da-índia, eugenol, imagens digitais. FOOD TECNHOLOGY