Information rich chromatographic separations of natural samples : the analysis of antioxidants in coffee using post column derivatisation and the CUPRAC assay on narrow bore reaction flow HPLC columns

In the present work, the CUPRAC PCD assay coupled to a narrow bore RF column (150 mm × 2.1 mm i.d., 5 µm particles) was tested on a variety of antioxidant standards and natural samples (coffee and decaffeinated coffee) to demonstrate the separation performance. As a result of being able to utilise narrow bore RF columns, several significant factors have been highlighted, including high resolution post column derivatisation assays and an approximate five-fold decrease in the volume of reagents (mobile phase and PCD reagents) resulting in a reduced cost of the analysis in terms of purchase price and waste disposal. Moreover, the CUPRAC antioxidant assay illustrates a variety of antioxidants in the coffee samples and also presents an extensive level of detection selectivity. Furthermore, the narrow bore RF PCD procedure reveals that caffeine was extracted from the coffee and yet a co-eluting antioxidant was not removed.