Extraction and determination of caffeine content in ground coffee commercially available on Bosnian market

Caffeine (1,3,7-trimethylxanthine) is an alkaloid that acts as a stimulant on the central nervous system. Caffeine consumption brings a momentary increase in awareness and alertness in humans, as well as in experimental animals. The refluxing method and the regular coffee preparation method were used to extract caffeine from several coffee varieties that were sold in Bosnia. TLC and melting point analysis were performed before and after purification using vacuum sublimation. Chemical characterization of samples by FTIR (Fourier Transform Infrared Spectroscopy) analysis was performed by comparing with caffeine standard spectra. The percentage of extracted impure caffeine was higher in coffee samples obtained by the ordinary brewing method compared to reflux. After purification of crude extracts, all refluxed samples yielded more caffeine than those prepared by conventional brewing. In developed TLC chromatograms, Rf values of samples and standard match the literary Rf values of caffeine. Unprocessed caffeine samples showed a melting point from 185 to 216°C, corresponding to the range of 180 to 220°C, the melting point of crude caffeine. After vacuum sublimation, the melting point of all samples was between 235 and 237 °C, which corresponds to the literary values (235-239 °C for the “Merck” caffeine standard). Comparing the FTIR spectra of samples and standard, characteristic caffeine signals were observed confirming successful caffeine isolation. The caffeine content in the analyzed coffee samples from the Bosnia and Herzegovina market complies with FDA (Food and Drug Administration) regulations on the daily amount of caffeine intake per cup of coffee.