Abstract: Of seven such compounds tested only loprazolam gave any significant emission after oxidation, e.g., by KMnO4. The optimum conditions used in a 0.5 mm i.d. PTFE tubing dual-flow injection system were: 0.2 mM KMnO4, with 0.94 M formic acid (at pH 0.9) as the carrier stream at 1.3 mL min-1 in both lines. The response was rectilinear between 10 µM and 5 mM for a 50 µL injection, and the limit of detection was 7 µM. Iron(II) and Mn(II) interfered. The method was applied in analysis of tablets, but results were rather higher than expected.

Abstract: Seven benzodiazepines (concentration. 1 mM) were examined for chemiluminescence in a flow injection system with various oxidizing and reducing reagents and water as carrier. Only loprazolam (I), with acidic KMnO4 as reagent, gave a measurable response. Optimum conditions for the determination of I were; water as solvent, 0.94 M formic acid, adjusted to pH 0.9 with HCl, as carrier, 0.2 mM KMnO4 as reagent, and a flow rate of 1.3 mL min-1 in the sample and reagent lines. The calibration graph was rectilinear from 0.01 to 5 mM I, and the detection limit was 7 µM. Of 12 metal ions examined, only Fe(II) and Mn(II) interfered. The method could be used to determine I in tablets; excipients did not interfere.