Determination of Caffeine and Elements in Hypertonic, Isotonic, and Hypotonic Beverages

Abstract

The study focused on the examination of eight commercial hypertonic, isotonic, and hypotonic beverage samples that were packaged in aluminum cans or polyethylene terephthalate (PET) bottles. The pH value, caffeine content, and concentration of thirty elements were determined. Caffeine quantification was performed by a high-performance liquid chromatography method. Element determination was conducted by using inductively coupled plasma–optical emission spectrometry. The results showed that pH values were much more acidic in all samples, ranging from 2.68 to 3.97. Caffeine concentrations ranged from 0.02–38.93 mg/100 mL between the samples and were found to be below the acceptable daily level (~400 mg) established by the relevant food regulatory authority. The measurable quantity of caffeine (~10 mg/100 mL) was found in two functional beverage samples where caffeine was labeled as an ingredient. Element concentration varied with statistically significant differences (p < 0.05) among all samples. Elements such as arsenic, cadmium, chromium, and lead were measured below the corresponding permissible levels set by the European Commission; however, daily consumption of functional beverages should be examined to deteriorate several health risks. Aluminum was quantified above the parametric value by 21 to 117% in the canned samples, whereas antimony was only measured in PET-bottled samples at approximately 3 μg/L. Multivariate methods were applied to investigate any possible correlation between the samples and the examined parameters. Strong positive correlations with statistically significant differences (R > 0.9, p < 0.05) were observed between zinc and copper and between calcium and silver. Finally, similarities and differences between the samples and the examined parameters resulted in satisfactory discrimination of them regarding not only their caffeine content but also their tonicity. Excessive consumption of functional beverages could represent a major public health issue due to elevated amounts of caffeine and elements. Consequently, the results of this research could facilitate the formulation of stricter standards in beverage consumption by revealing potential health hazards to consumers.