Simultaneous determination of methylxanthines in coffees and teas by UV-Vis spectrophotometry and partial least squares

• Published in: Analytica chimica acta Vol. 493; no. 1; pp. 83 - 94
• Main Authors: López-Martı́nez, Leticia, López-de-Alba, Pedro Luis, Garcı́a-Campos, Rosalinda, De León-Rodrı́guez, Luis M
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 23.09.2003; Elsevier
• Subjects: Analytical chemistry; Biological and medical sciences; Chemistry; Chromatographic methods and physical methods associated with chromatography; Coffee, tea and other stimulative beverage industries; Coffees; Exact sciences and technology; Food industries; Fundamental and applied biological sciences. Psychology; Methylxanthines; Other chromatographic methods; PLS; Spectrometric and optical methods; Standard addition; Teas; Methylxanthines; Teas; Standard addition; PLS; Coffees; Methylxanthines: Standard addition; HPLC chromatography; Theobromine; Coffees: Teas; Calibration; Xanthine; Coffee; PLS regression; Absorption spectrometry; Tea; Sample preparation; Simultaneous measurement; Caffeine; Ultraviolet visible spectrometry
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/S0003-2670(03)00862-6

This work describes a method to simultaneously determine caffeine (CF) and theobromine (TB) in coffee and tea samples using partial least squares (PLS-1). Sample preparation was required to eliminate strong interfering components. High-performance liquid chromatography (HPLC)-found concentrations of caffeine and theobromine (theophylline was not found in any analyzed sample) were used to construct universal calibration matrixes for coffee and tea. Due to the low levels of theobromine when compared to caffeine (up to 1000:1), theobromine addition standard was required to dramatically improve method performance. The method developed did not show statistically significant differences with an HPLC standard technique.