Identification power of a standardized HPLC-DAD system for systematic toxicological analysis

High-performance liquid chromatography with photodiode-array detection (HPLC-DAD) provides two identification parameters: retention and UV spectral data. The identification power of these two parameters, expressed in standardized form (retention index and absorption maximum with the highest wavelength), is calculated using two approaches: discriminating power (DP) and mean list length (MLL). Our own HPLC database, which comprises data for more than 370 substances, is used as the basis of calculations. The identification power of both parameters applied separately is low but increases substantially when the combination of retention and spectral data is applied. Additionally, the DP and MLL values obtained for 56 acidic or neutral and 76 basic drugs examined by means of HPLC-DAD and other analytical methods (thin-layer chromatography, gas chromatography (GC), and ultraviolet (UV) detection) are compared. The on-line combination of HPLC retention index values and UV spectra, registered by means of DAD, creates an identification system in which the identification potential is slightly lower than the off-line combination of capillary GC and UV spectroscopy.