Using a biphasic system and digital imaging analysis with chemometric tools for simultaneous determination of Cu2+ and furfural in cachaca

The present study reports, for the first time, the development and application of a highly efficient method based on digital imaging analysis for the simultaneous determination of Cu2+ and furfural in cachaca samples using a two-phase system and chemometrics tools. Furfural reacts with aniline in an acidic medium to form a Schiff base, which exhibits a pink color. On the other hand, Cu2+ reacts with cuprizone in a basic medium to form a blue complex. The two reactions were performed on a porcelain plate, and a smartphone was used to capture the colorimetric images. Partial least squares (PLS) regression was used to construct the prediction models for Cu2+ and furfural contents in cachaca samples. After finding the best PLS models, the ordered predictor selection (OPS) analysis was performed in order to select the most predictive variables. The method developed was found to be effective in estimating the amounts of Cu2+ and furfural in cachaca samples, with a mean absolute error of 0.2 mg L-1 for the Cu2+ model, and 0.3 mg per 100 mL of anhydrous alcohol for the furfural model. The method proposed in this study is simple and straightforward; it does not require complex technical knowledge and can be used by the producers themselves in the cachaca manufacturing process.

Automated summary

The study introduces a novel and efficient method for simultaneous determination of Cu2+ and furfural in cachaca samples using digital imaging analysis, two-phase system, and chemometrics tools. The method involves reactions between furfural and aniline in an acidic medium forming a pink Schiff base and between Cu2+ and cuprizone in a basic medium forming a blue complex. Partial least squares regression and ordered predictor selection analysis were used to construct prediction models and select the most predictive variables. The developed method showed high accuracy with mean absolute errors of 0.2 mg L-1 for Cu2+ and 0.3 mg per 100 mL of anhydrous alcohol for furfural. This simple method can be easily used by cachaca producers in the manufacturing process.