Determination of peptidoaminobenzophenone (2‐ o ‐chlorobenzoyl‐4‐chloro‐N‐methyl‐ N ′‐glycylglycinanilide) and its metabolites in human plasma by capillary gas chromatography negative ion chemical ionization mass spectrometry — 2

The capillary gas chromatographic negative ion chemical ionization mass spectrometric assay of peptidoaminobenzophenone (2‐ o ‐chlorobenzoyl‐4‐chloro‐ N ‐methyl‐ N ′ ‐glycylglycinanilide) (1) and its three metabolites in human plasma reported in Part 1 was changed as follows: (1) the reagent gas was changed to ammonia from isobutane; (2) each unlabelled compound (1%) was added to the deuterium‐labelled compound used as the internal standard; (3) all samples were injected in the splitless mode; (4) one more metabolite, lormetazepam, was determined; (5) day‐to‐day reproducibility was checked in the range of 1–50 ng ml −1 . Points 1 to 3 improved the preciseness with small‐sized samples. Calibration curves were prepared in the range of 0.5–50 ng ml −1 . Plasma levels of compound 1 and its four metabolites in 10 volunteers were measured.