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Analytical Techniques Used for Determination of Methylxanthines and their Analogues—Recent Advances

Methylxanthines (caffeine, theophylline, theobromine) are a popular group of natural purine alkaloids, which are components of many commonly used drugs, parapharmaceuticals and a wide range of food products (e.g. coffee, tea, energy drinks, etc.). Caffeine metabolites (theophylline, paraxanthine, theobromine and other 1-, 3-, 7-methyl tri-, di- and mono-derivatives of xanthine) and hypoxanthine metabolites (xanthine, uric acid) play an important role in the biochemical processes of mammalian organisms. That is why they are the markers of many diseases and are in the focus of the clinicians, pharmaceutical industry and ecologists. In addition to the natural methylxanthines there are structurally related synthetic derivatives: pentoxifylline, dyphylline, xantinol nicotinate and 8-chlorotheophylline that are still valuable pharmaceuticals needing to be monitored. A review of the modern techniques used for determination of methylxanthines for the last 10 years (2000 – March 2010) is presented.