Abstract
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.
Highlights
Caffeine (1,3,7-trimethylxanthine) is a stimulant of the central nervous system, relatively abundant in coffee and cacao beans, kola nuts, guarana berries and leaves of tea and yerba mate [1]
It is commonly assumed that caffeine reduces fatigue and enhances physical endurance, mental alertness and concentration
It is admitted that daily doses of caffeine below 250 mg are safe [4]
Summary
Caffeine (1,3,7-trimethylxanthine) is a stimulant of the central nervous system, relatively abundant in coffee and cacao beans, kola nuts, guarana berries and leaves of tea and yerba mate [1]. Caffeine is the most consumed alkaloid, mainly in beverages such as tea, coffee and soft drinks. Common medicines widely consumed possess caffeine as one of their active components [2]. Food and Drug Administration (FDA) regards caffeine either as a drug or a functional food [3]. It is admitted that daily doses of caffeine below 250 mg are safe [4]. Excessive consumption may cause accelerated heart rate, nervousness, anxiety and insomnia, in people still lacking tolerance to caffeine, such as children and teen agers [2]. Care is necessary regarding pregnant women, since high caffeine intake may have negative consequences on baby delivery and induce low weight of newborns [4]
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