Carmen Palacios^1,, Maria L. F. Salatino¹, Antonio Salatino¹

An inexpensive TLC method is proposed for quantification of caffeine in food and beverage commercial products. The extraction is carried out with dichloromethane and the residue is analyzed by thin layer chromatography. The chromatograms are sprayed with a reagent containing iodine for visualization and the area of the spots is determined by freely available software. A good correlation was observed between contents of caffeine and TLC spot areas. Quantification of caffeine was carried out for a medicine tablet, coffee and guarana powders, a kola soft drink and a yerba mate beverage. Values close to the contents expected or within the admitted ranges were obtained. The method may be inadequate if high precision is essential, but it might be useful if values approximate to the real caffeine contents are satisfactory. Since the method requires no costly equipment, it seems to be feasible for chemistry teaching at several academic levels.

general public, first-year undergraduate, laboratory instruction, thin layer chromatography, undergraduate research, food chemistry, alkaloids