A fast and efficient method for the study of caffeine levels in energy drinks using micellar electrokinetic chromatography (MEKC)

Abstract

Energy drinks are becoming popular in Brazil and in the world due to their stimulant properties. Caffeine is present in energy drinks with the aim of stimulating the central nervous system and intensifying brain activity. On the other hand, the ingestion of high doses of caffeine can cause undesirable symptoms such as anxiety and tachycardia. Therefore, it is necessary to monitor the caffeine content added to energy drinks to guarantee that the levels in the final product are in accordance with the labeling and within the legislation limits. The goal of this work was to validate a fast, efficient, and low-cost method for the determination of caffeine in energy drinks by micellar electrokinetic chromatography (MEKC). A total of seven brands were analyzed, each in three lots. The electrolyte was prepared with 50 mmol.L-1 of sodium dodecyl sulfate (SDS) and 10 mmol.L-1 of sodium carbonate (pH 11.0). The mean concentration of caffeine ranged from 122.8 to 318.6 mg.L-1. None of the brands had caffeine levels above the maximum limit. Considering the interval of confidence (95%), 72% of the samples had less caffeine than the amount informed on the product label.

Development of a method for simultaneous analysis of caffeine and taurine in energy drinks by micellar electrokinetic chromatography with diode-array detector

“…Regarding taurine content, 50% of the brands presented at least a batch above the maximum limit allowed. Similar results were found for caffeine by McCusker et al (2006) using gas chromatography with nitrogen-phosphorus detector, and by Ballus et al (2012) using the technique of micellar electrokinetic chromatography with DAD (MEKC) detection system. x 72 cm of effective length with extended bulb, electrolyte benzoic acid 16.2 mmol.L -1 with sodium dodecyl sulfate (SDS) 39.9 mmol.L -1 , pH 7.26, 30 kV, 25 °C, injection of 50 mbar for 5 s and detection at 274 nm (caffeine) and at 230 nm (taurine).…”

Caffeine content of energy drinks marketed in Brazil

“…15 On the other hand, Lage-Yusty et al (2019) quantified caffeine, vitamin B2, vitamin B6, and taurine in six energy drinks and concluded that most commercial samples did not comply with regulations in terms of the evaluated substances. 16 17,18 As mentioned previously, except for the energy drinks that were labeled as "nutritional supplements," we did not find any energy drink exceeding the limit of caffeine concentration allowed by Anvisa (35 mg/100 ml). Besides that, considering the doses stated on the labels, no energy drink exceeded the safe upper limit of caffeine consumption for healthy adults (400 mg).…”

Simultaneous and rapid determination of caffeine and taurine in energy drinks by MEKC in a short capillary with dual contactless conductivity/photometry detection

“…1. In this compact arrangement, the separation capillary (1), injection (2) and terminal (3) vessels, dual detection cell (4), electronic of the contactless conductivity detector (5), and (6) are placed under the shielding cover. The structural design of the C 4 D is taken from [22].…”

“…Alternating current is fed to one of the electrodes from a sinus voltage generator (5). The signal passing through the cell is recorded by the second electrode and, following amplification and rectification (6), is fed into a computer for registration.…”

“…The individual components are generally determined separately in beverages and energy drinks. For example, recently, works have been published describing the determination of caffeine based on MEKC with UV detection , MEEKC with UV detection , UV/Vis derivative spectrophotometry , and capillary chromatography in a monolithic column with UV detection . Caffeine has also been determined voltammetrically, for example, on a modified glassy carbon electrode or using a boron‐doped diamond electrode .…”