Analysis of xanthene dyes by reversed-phase high-performance liquid chromatography on a polymeric column followed by characterization with a diode array detector.

A high-performance liquid chromatographic method on a polymeric column was developed for the analysis of xanthene dyes. The rigid polystyrene-divinylbenzene column was connected to a photodiode array detector to verify the identity and the purity of the dyes. For eosin Y a within-day precision of 1-2% was obtained, and on a day-to-day basis the coefficient of variation was 4.2%. The purity of commercial xanthene dyes was investigated, and the results show the divergence between the actual dye contents and the dye contents indicated on the label.