Determinação de cafeína em bebidas estimulantes por cromatografia líquida e espectrofotometria UV-Vis

Abstract

Caffeine is one of the most legal drugs consumed in the world and its composition is present in some plants like guarana, mate, coffee and herbs, however, played an important role in producing beverages from an antiquity. In this context, this work this work aims to determine concentrations of caffeine, in samples of soluble coffee, tea, energy drinks, soft drink and caffeine supplement. Excessive consumption of these foods containing caffeine may pose risks to human health and, in the face of this problem, three energy drinks of different brands (E1, E2 and E3), three coffee samples, coffee common, gourmet and decaffeinated (C1, C2 and C3), two brands of tea, mate and black (T1 and T2), two common and caffeinated cola (R1 and R2), and a supplementation based on caffeine (S) were analyzed using two analytical methodologies: Liquid Chromatography and UV-Vis Spectrophotometry. In relation to the chromatographic analyzes the samples E1, E2 and E3 presented caffeine concentrations of 50,300; 53.316 and 55.256 mg / 200 mL, respectively. The samples of C1, C2 and C3 presented 5.520; 5,160 and 1,190 mg.g-1. Tea samples (T1 and T2) presented 22,135 and 76,320 mg.L-1. Black cola (R1 and R2) samples showed 21.886 and 32.438 mg / 220 mL and the caffeine supplement presented 468.65 mg / 530 mg. For the spectrophotometric analyzes only the C1, E1 and R1 samples were analyzed, considering the necessity of a great use of chloroform in the analyzes. In the spectrophotometric determination the sample C1 presented a caffeine concentration of 6,692 mg.g-1, the energy drink E1 of 66,500 mg/200 mL and that of cola-based refrigerant of 86.77 mg.L-1. The most feasible methodology was which required less work was that of Liquid Chromatography, since in the preparation of the samples there was the treatment with MgO for the reduction of interferes that could compromise the analysis.