A Determination of the Caffeine Content in Dietary Supplements According to Green Chemistry Principles

Abstract

Caffeine is a natural psychoactive substance that belongs to a group of chemical compounds called purine alkaloids. Caffeine is found in various plants such as coffee, tea, cocoa, guarana, and yerba mate. It is often added to dietary supplements for its ability to increase metabolism and aid in weight loss. To determine the caffeine content in dietary supplements, a novel UHPLC method was developed, compatible with the rules of green analytical chemistry. The developed method used only water and ethanol for sample preparation and chromatographic separation on a short C18 column. The obtained method confirmed that caffeine may be analyzed using only environmentally friendly solvents, ethanol, and water. The developed method is characterized by its low limit of quantitation, equal to 0.047 µg/mL, and good reproducibility (a relative standard deviation lower than 1.1%). The obtained results show that the caffeine content in tested dietary supplements is 4–35% higher than the declared amount in most cases. In comparison, the caffeine content of the drug determined using this method was performed with an accuracy of 0.4% RSD.

Comparative Analysis of Caffeine Content in Cold and Hot Brewed Robusta Coffee Using High-Performance Liquid Chromatography (HPLC)

“…One of the most effective and popular methods for determining caffeine content in beverages is high-performance liquid chromatography (HPLC). This method is highly accurate and widely utilized in the food and pharmaceutical industries [19]. The HPLC method allows for directly separating and identifying caffeine from other substances.…”

Elimination of Toxic Solvents from Analytical Methods in Food Analysis: Caffeine Determination in Tea as an Example

“…It is known that ethanol may be applied as an organic modifier for HPLC analysis due to its similar properties to acetonitrile [32][33][34]. Recently, a green method of caffeine determination in dietary supplements was published [35]. For this reason, it is reasonable to ask whether ethanol can also replace organic solvents used in the sample preparation stage, for example, in the SPE technique.…”