Development of an HPLC method for the toxicological screening of central nervous system drugs

A simple and sensitive HPLC (high performance liquid chromatography) method has been developed for the qualitative and. quantitative analysis of several CNS (central nervous system) drugs in clinical and forensic toxicology. The leading conditions were studied, namely parameters such as mobile phase pH, organic modifier percentage, and salt concentration An isocratic HPLC elution, using a mobile phase composed of acetonitrile and pH 2.8 aqueous tetramethylammonium perchlorate and a C8 reversed phase column as the stationary phase, was found to be convenient for the separation of several CNS drugs, and for their detection and quantitation. The identification of the drugs was assured using their relative retention times, together with the peak area ratios at two different wavelengths (230 and 270 nm). A quick pre-treatment of the plasma samples, based on a SPE (solid phase extraction) procedure, with good extraction efficiency and satisfactory selectivity was developed. Under these conditions, a mixture of fifteen CNS drugs (including antipsychotics, antidepressants and antiepileptics) and some selected active metabolites, was well separated for identification and quantitative determination purposes.