doi:10.1007/s00216-024-05401-xengDomínguez, M.Moraru, D.Lasso, S.Sanz-Vicente, I.Marcos, S. deGalbán, J.Colorimetric enzymatic rapid test for the determination of atropine in baby food using a smartphoneART-2024-139768A method for the enzymatic determination of atropine has been developed, which is based on a sequence of reactions involving (1) the hydrolysis of atropine to give tropine; (2) the enzymatic oxidation of tropine with NAD (catalysed by tropinone reductase); and (3) an indicator reaction, in which the NADH previously formed reduces the dye iodonitrotetrazolium chloride (INT) to a reddish species, the reaction catalysed by diaphorase. The method was first developed in solution (linear response range from 2.4 × 10−6 M to 1.0 × 10−4 M). It was then implemented in cellulose platforms to develop a rapid test where the determination is made by measuring the RGB coordinates of the platforms using a smartphone-based device. The device is based on the integrating sphere concept and contains a light source to avoid external illumination effects. The smartphone is controlled by an app that allows a calibration line to be generated and the atropine concentration to be quantified; moreover, since the app normalizes the CCD response of the smartphone, the results and calibrations obtained with different smartphones are similar and can be shared. Using the G coordinate, the results were shown to have a linear response with the concentration of atropine ranging from 1.2 × 10−5 M to 3.0 × 10−4 M with an RSD of 1.4% (n = 5). The method has been applied to the determination of atropine in baby food and buckwheat samples with good results.2024http://zaguan.unizar.es/record/14496910.1007/s00216-024-05401-xhttp://zaguan.unizar.es/record/144969oai:zaguan.unizar.es:144969info:eu-repo/grantAgreement/ES/DGA/E25-23Rinfo:eu-repo/grantAgreement/ES/MICINN/PID2019-105408GB-I00info:eu-repo/grantAgreement/ES/MICINN/PID2022-139235OB-I00Analytical and Bioanalytical Chemistry 416 (2024), 7317–7323byhttps://creativecommons.org/licenses/by/4.0/deed.esinfo:eu-repo/semantics/openAccess