Identification of drugs in human serum by high-performance liquid chromatography with photodiode array detection and a search algorithm for ultraviolet spectra.

A system is described that identifies a number of unknown drugs (benzodiazepines, antidepressants and neuroleptics) in blood specimens for clinical-toxicological purposes. Reversed ion-pair high-performance liquid chromatography with a photodiode array detector saves the ultraviolet spectrum of every chromatographically significant peak. Post-run data-processing, provided by a microcomputer, retrieves candidate substances from a library of ultraviolet spectra. Selected standard ultraviolet spectra are compared with the unknown by five different similarity tests. The discriminatory efficiency of these algorithms has been determined. Multicomponent analysis, a built-in program of the spectrophotometer, provided the most reliable results.