Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10561166 | Talanta | 2005 | 7 Pages |
Abstract
In order to improve the chromatographic resolution (Rs) with a good analysis time, experimental designs were applied for multivariate optimisation of the experimental conditions of an isocratic reversed-phase high-performance liquid chromatographic (RP-HPLC) method used for the simultaneous determination of caffeine, theobromine and theophylline. The optimisation process was carried out in two steps using full three-level factorial designs. The factors optimised were: flow rate and mobile phase composition. Optimal conditions for the separation of the three methylxanthines were obtained using a mixture of water/ethanol/acetic acid (75:24:1%, v/v/v) as mobile phase and a flow rate of 1.0 mL minâ1. The RP-HPLC/UV method was validated in terms of limit of detection (LOD), limit of quantitation (LOQ), linearity, recovery and the precision, calculated as relative standard deviation (R.S.D.). In these conditions, the LOD was 0.10 μg Lâ1 for caffeine, 0.07 μg Lâ1 for theobromine and 0.06 μg Lâ1 for theophylline. The proposed method is fast, requires no extraction step or derivatization and was suitable for quantification of these methylxanthines in coffee, tea and human urine samples.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Nádia M. de Aragão, Márcia C.C. Veloso, Márcia Souza Bispo, Sérgio L.C. Ferreira, Jailson B. de Andrade,