Luchiari Natália da Costa, da Silva Gabrielen Alves, Marasco Júnior César Augusto, de Lima Gomes Paulo Clairmont Feitosa
Department of Analytical Chemistry, Unesp, National Institute for Alternative Technologies of Detection, Toxicological Evaluation and Removal of Micropollutants and Radioactives (INCT-DATREM), Institute of Chemistry P.O. Box 355 14800-900 Araraquara (SP) Brazil
RSC Adv. 2019 Oct 30;9(60):35033-35038. doi: 10.1039/c9ra06220c. eCollection 2019 Oct 28.
Caffeine is an element that is consumed worldwide. It is present in many products such as beverages, chocolate, coffee, tea, energy drinks and medicines. Portable 3D devices working together with colorimetric and fluorimetric reactions have been able to determine the presence of caffeine in different kinds of samples. Also, digital image-based methods using smartphones have conferred portability and accessibility to miniaturized devices that are innovative and promising options for quick and low cost analyses. This study proposes a miniaturized fluorimetric device to determine caffeine by digital image using a smartphone. The OpenCamera app was used to capture images that were processed using ImageJ software to obtain RGB channels values. The red (R) channel signal intensity was selected as the analytical response. The device developed was applied to determine caffeine in an energy drink and medicines. The method developed presented a linear range from 100 to 600 mg L of caffeine, and quantification (LOQ) and detection (LOD) limits of 100 mg L and 30.0 mg L, respectively. The caffeine concentration found in the products analyzed was 328 mg L (±2.5%) for the energy drink, 345 mg L (±15%) for medicine A and 322 mg L- (±7.3%) for medicine B. The proposed device presented important characteristics such as low cost, required small volumes of reagents and samples, quick analysis, portability and suitable to be applied in complex matrices.
咖啡因是一种在全球范围内都有人消费的元素。它存在于许多产品中，如饮料、巧克力、咖啡、茶、能量饮料和药品。便携式3D设备与比色和荧光反应协同工作，已能够测定不同种类样品中咖啡因的存在。此外，使用智能手机的基于数字图像的方法赋予了小型化设备便携性和可及性，这些设备是用于快速和低成本分析的创新且有前景的选择。本研究提出了一种使用智能手机通过数字图像测定咖啡因的小型化荧光设备。使用OpenCamera应用程序捕获图像，然后使用ImageJ软件对图像进行处理以获得RGB通道值。选择红色（R）通道信号强度作为分析响应。所开发的设备用于测定能量饮料和药品中的咖啡因。所开发的方法呈现出咖啡因浓度在100至600 mg/L之间的线性范围，定量限（LOQ）和检测限（LOD）分别为100 mg/L和30.0 mg/L。在所分析的产品中，能量饮料中的咖啡因浓度为328 mg/L（±2.5%），药品A中的咖啡因浓度为345 mg/L（±15%），药品B中的咖啡因浓度为322 mg/L（±7.3%）。所提出的设备具有重要特性，如成本低、所需试剂和样品体积小、分析快速、便携且适用于复杂基质。
