Use of colour co-ordinates and peak purity parameters for improving the high-performance liquid chromatographic qualitative analysis of dyes

Abstract

Spectra for acidic dyes chromatographed on a polymeric packing material were recorded with a high-performance liquid chromatography multi-wavelength detector. From these results the complementary chromaticity co-ordinates (CCC) were calculated, together with two peak purity parameters (PPP) covering the spectral ranges 220–600 nm (ultraviolet-visible) and 380–600 nm (visible). For acidic monoazo dyes the PPP and CCC values show a relative standard deviation of less than 1% for 25-ng samples. Both PPP and CCC values remain constant for injected amounts of up to 2.5 µg. The application of these PPP and CCC techniques to provide qualitative information for sample discrimination and structural identification is described.