[Determination of benzodiazepines by thermospray liquid chromatograph-mass spectrometer. Part 1. Nitrazepam, estazolam, bromazepam, flunitrazepam].

Thermospray liquid chromatography mass spectrometric method is described for the determination of the benzodiazepines (Nitrazepam, Estazolam, Bromazepam, Flunitrazepam). Reversed-phase liquid chromatography was performed using a 15 cm Shim-pack CLC-ODS (Shimadzu) column, with acetonitrile-water (40:60) + 0.1 M ammonium acetate as mobile phase, at a flow rate of 1.0 ml/min. The temperature of the vaporizer, block and TH of the source block were 166, 270 and 275 degrees C, respectively. Positive ion thermospray mass spectra by thermospray ionization (TSP ionization) mode or thermospray on filament ionization (filament-on ionization) mode were obtained. Formation of the MH+ ion was observed as a base peak under TSP ionization and filament-on ionization conditions and fragment ions were very few. On both ionization mode, peaks representing nitrazepam as MH+ at m/z 282 at a retention time (R.T.) of 6.4 min, from estazolam as MH+ at m/z 295 at an R.T. of 6.4 min, from bromazepam as MH+ at m/z 316 at an R.T. of 4.5 min and from flunitrazepam as MH+ at m/z 314 at an R.T. of 8.8 min. The detection limit for all the benzodiazepines under investigation was less than 0.5 ng (S/N = 9.4 +/- 4.6) using selected ion monitoring.