Capillary gas chromatographic (GC) analysis of nitroglycerin and its denitration products in plasma

A convenient, specific, and sensitive capillary gas chromatographic (GC) assay for analyzing nanogram concentrations of nitroglycerin and its dinitro- and mononitrometabolites in plasma has been developed. Using a bonded-phase (DB-1) 30-m, 1-micron-thick film capillary column and a 1-m, 5-microns-thick film precolumn, separation of nitroglycerin and all four partially nitrated metabolites was achieved in less than 15 min. On-column injection, electron capture detection, and isothermal operation at 100 degrees C yielded a linear extraction curve over a 300-ng/ml range without any need to concentrate sample extracts. Using methyl t-butyl ether as extraction solvent and o-chloronitrobenzene as internal standard, recoveries from plasma spiked at levels greater than 10 ng/ml approximated 35% for the 1-monometabolite, 40% for the 2-monometabolite, and greater than 90% for all others. The method was employed in a pharmacokinetic study of nitroglycerin administered intravenously to beagle dogs. Plasma samples were collected at various time points and analyzed.