Smartphone-based colorimetric detection using gold nanoparticles of sibutramine in suspected food supplement products

Abstract

© 2020 Elsevier B.V. Sibutramine has been used as an appetite suppressant for many years. However, it was withdrawn from markets in several countries due to its fatal side effects. Adulteration of food supplement products with sibutramine has been found in the markets. In this study, a simple and portable colorimetric test using a smartphone and gold nanoparticles (AuNPs) for sibutramine analysis is proposed. The aggregation of citrate-stabilized AuNP in the presence of sibutramine leads to a color transition from wine red to blue, which was verified by UV–Vis spectrophotometry and transmission electron microscopy (TEM) technique. The change of solution color is visible by the naked eye and can be monitored with a smartphone. The ratio of green and red colors in a photo recorded by a smartphone was linearly related to the sibutramine concentration in the concentration range 5–15 µM (R2 = 0.979). The limit of detection and limit of quantification were 1.15 µM and 3.47 µM, respectively, without any effects from potential interferences or sample matrix. The intra-day and inter-day precisions were 0.8–2.0 %RSD and 0.7–2.0 %RSD, respectively. Accuracy of sibutramine detection ranged from 92 to 107%. The developed method was successfully employed to detect sibutramine in six adulterated products, and the results were in good agreement with those from UV–Vis spectrophotometry with relative error in the range −9.3 to 1.7%. A simple, rapid, and portable method can be used as an alternative approach to detect and quantify this misused substance, without need for any sophisticated instrumentation.