Digital techniques for luminescence detection in liquid chromatography with an intensified linear photodiode array

The use of a rapid-scanning fluorescence detector in liquid chromatography is examined in the context of its potential contribution in pharmaceutical and biomedical analysis. The data generated by an intensified linear photodiode array detector is presented as an isometric plot of (I(em),lambda(em),t) at a defined excitation wavelength. Techniques examined for peak homogeneity assessment include: emission spectral normalisation at points through the chromatographic peak profile, second order differentiation (d(2)I/dt(2)) and the fluorescence emission ratio chromatogram, generated by calculating the ratio of emission intensifies at two defined emission wavelengths, at all points in the time domain elution profile. These techniques are illustrated with reference to some polynuclear aromatic hydrocarbons and to the beta-blocker drug atenolol and its related impurities. Future developments of this new detector technology in LC are also considered.