Analytical methods for quantitation of methylxanthines.

The methylxanthines can be determined in foods and biological systems by the chromatographic methods of TLC, GC, and HPLC. Ultraviolet spectroscopy following a separation procedure is also still used. More recently immunoassay methods have been developed. There is no single best method; the analyst must balance the features of each assay with the final requirements for data precision and reproducibility.