Mixed phases of Superox 20M and OV-1 in fused silica and glass capillary gas chromatography

Amphiphilic tocopheryl polyethylene glycol succinate as gas chromatographic stationary phase for high-resolution separations of challenging isomers and analysis of lavender essential oil

This work presents the investigation of using tocopheryl polyethylene glycol succinate as the stationary phase for gas chromatography separations of isomers with different varieties and gas chromatography-mass spectrometry analysis of a wide range of components in lavender essential oil. Its capillary column exhibited moderate polarity and column efficiency of 4000 plates/m determined by n-dodecane at 120°C. As demonstrated, it showed outstanding separation performance toward challenging isomers such as xylenes, alkanes, phenols, and anilines and a wide range of components in essential oils with distinct advantages over the commercial polyethylene glycol and polysiloxane columns. Moreover, its capillary columns displayed excellent repeatability and reproducibility with the RSD values of the retention times in the range of 0.02-0.07% for run-to-run, 0.14-0.22% for day-to-day, and 2.5-4.3% for column-to-column. Its application to gas chromatography-mass spectrometry analysis of the lavender essential oil proved its good potential for practical gas chromatography analyses. To our knowledge, this work presents the first example of employing tocopheryl polyethylene glycol succinate for chromatographic analyses and demonstrates its promising future in this field.

Highly sensitive assay of benzodiazepine antagonist in plasma by capillary gas chromatography with nitrogen-selective detection

A selective and highly sensitive capillary gas chromatographic method was developed for the determination of a benzodiazepine antagonist in human plasma. The analytical procedure involved extraction of the compound and its internal standard from basified plasma with n-butyl chloride-dichloromethane and chromatography of the extract on a DB-5 fused-silica column (30 m X 0.25 mm I.D.), applying automated splitless injection and nitrogen- phosphorus detection. The limit of quantification was about 50 pg/ml, using a 1-ml plasma specimen. The mean inter-assay precision was 2.6% in the concentration range 0.5-10 ng/ml. The method was shown to be specific with respect to various benzodiazepines and their main metabolites. The practicability of the method was demonstrated by the analysis of more than 300 plasma samples from a dose proportionality study performed with human volunteers. Owing to its high sensitivity, the new method can be used to obtain pharmacokinetic parameters of the benzodiazepine antagonist in man after doses near the envisaged therapeutic intravenous dose of less than 1 mg.