No abstract

A rapid UPLC-ESI-MS method was developed for simultaneous determination of caffeine and taurine in beverages (energy drinks and soft drinks). The molecular ions of caffeine and taurine were identified in single ion recording mode at m/z 194.98 and 125.86, respectively. The mass spectrometer parameters were optimized as: capillary voltage 3.0 kV, cone voltage 35 V, extractor 3 V, RF Lens 0.1 V, source temperature 150 °C, desolvation temperature 350 °C, nitrogen 600 L/h, LMR1 7.9, HMR1 15.2, IE1 0.30. The mobile phase comprising methanol (0.1% formic acid) (A) and water (5 mM ammonium acetate) (B) was used in gradient mode. The mobile phase components A and B were pumped in 80:20 (v:v) ratio from 0-0.44 min, and then 100% of component A was pumped between 0.45-0.68 min, and at 0.69 min the composition was returned to 80:20 (v:v) ratio of A and B till 2.0 min. Caffeine and taurine were eluted at 0.46 and 0.43 min, respectively. The samples of energy drinks and soft drinks were diluted in a solvent system comprising methanol and water in 80:20 (v:v) ratio. Our investigations showed that soft drinks SD1 and SD2 have 88.8±4.2% and 110.7±3.6% (w:w) caffeine of their labeled claim. The caffeine content in energy drink brands ED1, ED2, ED3, and ED4 was 76.9±2.5, 65.6±3.4, 88.1±12.6, and 89.1±2.8% (w:w) of labeled claims, respectively. While taurine content in ED1, ED2, ED3, and ED4 was 86.5±8.4, 81.3±27.5, 101.9±4.8, and 97.1±0.3% (w:w) of labeled claim, respectively.

Background: Multi-vitamin formulations are indicated for the elderly, adults, children’s and infants; to prevent or restore vitamin deficiencies. Objective: To provide a validated high-throughput method for simultaneous determination of vitamins in multi-vitamin formulations. Methods: A high-throughput UPLC-ESI-MS method was developed and validated for simultaneous determination of vitamins B1, B2, B3, B5, B6, B7 and B9. Analytes were eluted on an Acquity UPLC®BEH C18 1.7 μm, 2.1 x 50 mm column at 40 ± 5°C. Mobile phase containing acetonitrile (0.1% formic acid) and water (0.1% formic acid) in 30:70% ratio was pumped at 300 μL/min, under isocratic control. Protonated ions of vitamin B1, B2, B3, B5, B6, B7 and B9 were monitored in single ion recording mode, using electrospray ionization probe in positive mode. Results: The m/z ratio of positive ions of vitamin B1, B2, B3, B5, B6, B7 and B9 were 265.1, 377.2, 122.95, 220, 169.98, 244.9, and 442.1; respectively. The calibration curve of different linearity range (ng/ml) was prepared for each vitamin. Linearity range for vitamin B1, B2, B3, B5, B6, B7 and B9 were 60-1000, 25-1000, 75-5000, 30-1000 and 25-1000 ng/mL; respectively. Coefficient of variation for intra-day and inter-day precision for vitamin B1, B2, B3, B5, B6, B7 and B9; at middle and higher limit of quantitation were less than 15%. Conclusion: The method was successfully developed and validated, and three different brands of multi-vitamin tablets were assayed for water soluble vitamins.