Digital Image Method Smartphone-Based for Furfural Determination in Sugarcane Spirits

A novel, simple, and low-cost analytical procedure for in situ furfural determination in sugarcane spirit (cachaça) samples based on the combination of a colorimetric spot test and a digital image-based (DIB) method is proposed. Cachaça is the most consumed beverage in Brazil and the fourth in the world, and furfural is a contaminant that depreciates the quality and safety of this product. The proposed method is based on the reaction of furfural with aniline in acid medium, in which the colorimetric product was acquired using spot test; a digital image was captured with a smartphone camera. The digital images were decomposed by an RGB approach using a free software. The dynamic linear range to determine furfural was linear from 1.67 to 10.0 mg/100 mL (anhydrous ethanol; r = 0.998) with limits of detection and quantification of 0.34 and 1.15 mg/100 mL, respectively. The method was developed and applied for determination of furfural in unaged cachaça samples with satisfactory results. The recovery of furfural ranged from 85.7 to 106 %. The DIB method coupled to spot test is a viable and important alternative to determine some analytes such as furfural during the production of alcoholic beverages. In fact, the method is accurate, fast, and reproductive with a low waste generation (600 μL/spot test), being useful analytical tools for laboratory with limited financial resource and for green chemistry purposes.