Simultaneous determination of riboflavin, pyridoxine, nicotinamide, caffeine and taurine in energy drinks by planar chromatography-multiple detection with confirmation by electrospray ionization mass spectrometry

A new high-throughput method was developed to detect simultaneously riboflavin (Vitamin B2), pyridoxine (Vitamin B6), nicotinamide (Vitamin B3), caffeine and taurine in energy drinks by multiple detection. Ten samples of energy drinks and six samples of beverages containing caffeine were prepared by degassing in an ultrasonic bath for 20 min. After chromatography, multi-wavelength scanning was performed by: (1) UV-absorbance measurement at 261 nm for nicotinamide and 275 nm for caffeine, (2) fluorescence measurement at 366/>400 and 313/>340 nm for riboflavin and pyridoxine, respectively, and (3) Vis-absorbance measurement at 525 nm for taurine, after post-chromatographic derivatization with ninhydrin reagent. Calibrations were linear or polynomial with determination coefficients r2 > 0.999. Overall recoveries of the five compounds were between 81 and 106% at three different concentration levels. Repeatabilities (RSD, %) of all substances in matrix were determined to be between 0.8 and 1.5%. Intermediate precisions (RSD, %) ranged between 3.6 and 7.4% for riboflavin, 2.8 and 6.3% for nicotinamide, 2.5 and 4.4% for caffeine, 2.1 and 2.9% for taurine and 0.5 and 4.0% for pyridoxine at different concentration levels. Mass confirmation was performed by a single quadrupole MS in positive electrospray ionisation (ESI) scan mode for all substances except taurine (negative mode). This method offers a good alternative for routine analysis due to its simplicity and at the same time reliability.