An homologous series of benzodiazepine retention index standards for gas chromatography

An homologous series of benzodiazepine retention index standards (the R-series) has been synthesized and the gas chromatographic behavior of the series investigated on NB-54 and NB-1701 capillary columns. The compounds were stable, exhibited symmetrical peak shapes, and fairly linear retention behavior was observed on both columns. The series can be coinjected with every sample to enable the high precision analysis of toxicological samples; screening for 20 benzodiazepine drugs was possible in 23 minutes (including cooling). The R-series method was compared with a retention index method based on a series of benzodiazepine drugs as standards and with a method employing relative retention times. The precision of the R-series method was found to be generally better than that of the two other methods in both long- and short-term studies.