Simultaneous Determination of Caffeine and Taurine in Energy Drinks by Micellar Electrokinetic Chromatography in Short Separation Capillary
Abstract
A method has been developed for the rapid and simultaneous determination of taurine and caffeine using a laboratory-made instrument enabling separation analysis in a short 10.5 cm capillary. The substances are detected using a contactless conductometry / UV photometry detector that enables recording both signals at one place in the capillary.
The separation of caffeine and taurine was performed using the MEKC technique in a background electrolyte with the composition 40 mM CHES, 15 mM NaOH and 50 mM SDS, pH 9.36. Under these conditions, the migration time of caffeine is 43 s and of taurine 60 s; LOD for caffeine is 4 mg L-1 using photometric detection and LOD for taurine is 24 mg L-1 using contactless conductometric detection.
The standard addition method was used for determination in Red Bull energy drink of caffeine 317 mg L-1 and taurine 3860 mg L-1; the contents in Kamikaze drink were 468 mg L-1 caffeine and 4110 mg L-1 taurine. The determined values are in good agreement with the declared contents of these substances.
RSD does not exceed 3%.