Gunnar A. Ulsaker

Identification of caprolactam as a potential contaminant in parenteral solutions stored in overwrapped PVC bags

Semipreparative liquid chromatographic separation and subsequent off-line mass spectrometry have revealed caprolactam as a new contaminant in intravenous solutions. The content of the lactam was found to be 1.2-15.0 mg l-1 determined by liquid chromatography. Contamination is attributed to migration of caprolactam from the protecting plastic envelope through the PVC barrier and into the intravenous solution. Migration occurs during the final heat sterilization process.

Gas chromatographic-mass spectrometric identification of four triene monoepoxides of arachidonic acid in human plasma

Four triene monoepoxides of arachidonic acid have been identified as endogenous components of human plasma, the epoxy groups being in the 5,6-, 8,9-, 11,12- and 14,15-positions. Prior to trimethylsilylation and gas chromatographic-mass spectrometric analysis, both the expoxy and ester functions were reduced to hydroxy groups and the double bonds were hydrogenated catalytically. Saturation of the double bonds gave diagnostic spectra that were suitable for elucidating the position of the epoxy group. The shift in the fragmentation of a deuteriated sample verified the presence of the intact epoxides prior to chemical reduction. The presence of the double bonds in the epoxy molecules was demonstrated by reduction using homogeneous catalysis with tris(triphenylphosphine)rhodium(I) chloride and deuterium.

Gas chromatographic-mass spectrometric identification of 9,10-epoxyoctadeca-12-enoate ester and 12,13-epoxyoctadeca-9-enoate ester in human blood

The two epoxides 9,10-epoxyoctadeca-cis-12-enoate ester and 12,13-epoxyoctadeca-cis-9-enoate ester have been identified as endogenous components in human blood. The epoxy and ester function were reduced with either lithium aluminium hydride or the corresponding deuteride, before trimethylsilylation and subsequent gas chromatographic-mass spectrometric analysis. The fragmentation of the deuterated sample demonstrated the presence of the intact epoxide in the sample prior to chemical reduction. The sum of the identified epoxides in plasma was found to be 4.5–4.6 mg l–1.

Dealkylation and rearrangement of phenacylammonium salts in a gas chromatographic injector

Abstract Pyrolysis of aryl substituted phenacylbenzyldimethylammonium compounds was studied in a gas chromatographic injector. The thermal decomposition products were identified by gas chromatography/mass spectrometry. The influence of bromide and boron tetrafluoride anions on the pyrolysis was studied. The major process concerning the bromide ion was dealkylation via loss of the benzyl group; the minor process was dealkylation via loss of the phenacyl group. In both cases corresponding tertiary amines were formed. When the non-nucleophilic boron tetrafluoride was used as anion, no dealkylation occurred; the benzyl group rearranged and a tertiary amine was formed. The gas flow-rate (8–38 ml min −1 ) and the injector temperature (250–400°C) had minimal influence on the rearrangement.