Microanalysis based on paper device functionalized with cuprizone to determine Cu in sugar cane spirits using a smartphone.

In this work we propose for the first time, a paper-based test strip to analyse Cu content in sugar cane spirits, which, due to its simplicity, high portability and fast analytical response (3 min), can be easily applied to in situ analyses by producers. The test strip was developed aiming: i) identify qualitatively the Cu content in sugar cane spirits, and, ii) determine quantitatively the Cu content using a digital image method employing a smartphone. The paper-based test strip was functionalized with cuprizone and optimized through a Box-Behnken, an experimental design for obtaining the best reaction conditions.