Uso de imagens digitais para determinação quantitativa de metanol em bebidas alcoólicas

Abstract

Concerned about sustainability, analytical chemists have developed chemical analysis procedures that aim to minimize the consumption of reagents and samples combined with the reduction of operating costs. Thus, in recent years, Digital Image Based (DIB) methods have often been used as an alternative to quantitative determinations in analytical chemistry, especially in samples of environmental interest, food, beverages and drugs. This work proposes a method based on digital images for the determination of methanol in alcoholic beverages. The proposed system uses a scanner to acquire images generated according to the RGB (Red, Green, Blue) system. The determination of methanol is based on an oxidation reaction of methanol. After the reaction an image is captured and a region of the image is selected for decomposition of the pixels into the values of the RGB components. The analytical curve is obtained by relating the logarithm of the ratio between the white solution standard and the norm of the calibration solutions as a function of the concentrations of these solutions. The methanol content was determined in (mL / 100 mL of anhydrous alcohol) in the samples of cachaça, brandy and liqueur of jambú, cupuaçu and cocoa. In order to illustrate the viability of the proposed method, analyzes were performed on seven beverage samples. The results were compared with those obtained by spectrophotometry and when applying the paired t-test it was found that there was no statistically significant difference between the results obtained with the two methods at a 95% confidence level.