| Summary: | 碩士 === 高雄師範大學 === 化學系 === 97 === This research tries to use the Octadecylsilane(ODS) for packing solid phase extraction (SPE) to have the concentration effect and then the SPE connects with the high performance liquid chromatography(HPLC) to detect the trace catechins in the tea drinks. By using the physical absorption nature of ODS to absorb the catechins and caffeine, the on-line SPE first concentrates the analytes. Then the analytes are desorbed by the gradient elution of mobile phase and analysed by HPLC.
The experimental results show that it is effective to separate the catechins and the caffeine (GC, C, EGC, Caf, EC, EGCG, GCG, ECG, CG) by using the on-line SPE-HPLC. The linear correlation coefficient is above 0.998. The detection limits are below 5 μg/L, one tenth of the detection limits with the direct HPLC analysis method. The ODS-solid-phase extraction has the enrichment factors of 49.48, 80.57, 92.87, 81.58, 67.82, 64.79, 104.59, 43.05, and 75.55 correspond to GC, C, EGC, Caf, EC, EGCG, GCG, ECG, and CG, respectively.
Finally, we try to determinate the catechins and caffeine content of the real tea drinks by using the on-line SPE-HPLC. The result shows that the recoveries of the real tea drinks are between 100% ± 20% ( except GC, C). So the on-line SPE-HPLC has the advantages for reducing the sample loss, reducing pre-process and having automation for detecting the catechins and caffeine content. It is able to achieve the goal of the lowering the detection limits by the SPE concentration effect.
|
|---|
