Analysis of Consumer Products: Demonstrating the Power of LC-MS/MS for the Simultaneous Analysis of Caffeine and Other Methylxanthines in Guaraná Fruit Powder Extract

• Luzia P. Novaki ^[2] ; Ana M. Chinelatto ^[1] ; Vânia A. B. B. Silva ^[1] ; Omar A. El Seoud ^[1]
  1. [1] Universidade de São Paulo

     Universidade de São Paulo

     Brasil

     
  2. [2] ABC Federal University, Brazil
• Localización: Journal of chemical education, ISSN 0021-9584, Vol. 98, Nº 6, 2021, págs. 2083-2089
• Idioma: inglés
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• Resumen

  • Dilute guaraná (Paullinia cupana) powder aqueous extract is a soft drink that contains three structurally related methylxanthines (MXs), caffeine (CF), theobromine (TB), and theophylline (TP); CF is present in a large excess. Literature data show that values of λmax and εmax of these three MXs are very close. Consequently, quantitative analysis using a single technique (UV–vis) is difficult, at best. We asked our students how to determine the three MXs simultaneously. They suggested use of chromatographic separation followed by mass spectrometry (MS) detection. Use of electrospray ionization solved the MX structure identification problem only partially because TB and TP have the same molar mass. Using LC-MS/MS solved this problem, as TB and TP have distinct retention times and fragmentation patterns. This is an important everyday situation (analysis of foods and drinks) because of the popularity of CF-containing drinks (guarana, coffee, tea, cacao) and health concerns about abuse of CF consumption.