In this study, we have described a miniaturized, simple, and low-cost device for sulfite determination in beverages by coupling Gas Diffusion Microextraction to paper-based analytical devices. The color change of an acid-base indicator – promoted by the generated gaseous SO₂ – impregnated onto the paper surface was monitored in the function of time by video recording using a smartphone. The analytical information was related to the Hue, Saturation, Value (HSV) color space extracted from the video file. The complete analytical platform was built using a 3D printer, allowing the easy fabrication of a low-cost tailored device. Under optimized conditions, a linear relation from 5 to 90 mg L^-1 was obtained using 30 µL of the reagent, 1 mL of sample, and 10 min of analysis. The relative standard deviation and the limit of detection were 2.2% and 1.6 mg L^-1, respectively. The method was successfully employed in several beverages, such as juices, soda, and coconut water.

在这项研究中，我们通过将气体扩散微萃取与纸基分析设备相结合，描述了一种用于饮料中亚硫酸盐测定的小型化、简单且低成本的设备。酸碱指示剂的颜色变化——由产生的气态 SO ₂促进——浸渍到纸张表面，通过使用智能手机进行视频记录来监测时间的函数。分析信息与从视频文件中提取的色调、饱和度、值 (HSV) 颜色空间相关。完整的分析平台是使用 3D 打印机构建的，可以轻松制造低成本的定制设备。在优化条件下，线性关系从 5 到 90 mg L ^-1使用 30 µL 试剂、1 mL 样品和 10 分钟分析获得。相对标准偏差和检测限分别为2.2%和1.6 mg L ^-1。该方法已成功应用于多种饮料，例如果汁、苏打水和椰子水。