Applications of an HPLC-DAD Drug-Screening System Based on Retention Indices and UV Spectra

An analytical database, using high-performance liquid chromatography (HPLC) with diode array ultraviolet (UV) detection, of over 250 toxicologically relevant drugs has been extensively applied to both clinical and forensic toxicology. This general drug screening system, based on a mixed-phase (octadecyl/cyanopropyl) column and gradient reversed-phase HPLC, can identify a wide range of basic, acidic, and neutral drugs and metabolites, some of which are not amenable to gas chromatography and thin-layer chromatography. Compounds are identified using both retention index (RI) value (calculated by interpolation between a series of reference drug markers) and UV spectral data. It has been previously shown that this chromatographic system provides long-term reproducibility and has potentially useful selectivity differences compared with those based on octadecylsilane columns. Development has been undertaken to improve the speed and practicality of the system for emergency toxicology screening by increasing the rate of the elution gradient, while maintaining the applicability of the RI database. The database has also been found to be an important tool in determining optimum strategies for the adaptation of the system for quantitative analyses of drugs and metabolites under isocratic conditions.