Use of Capillary Gas Chromatography with Negative Ion-Chemical Ionization Mass Spectrometry for the Determination of Perfluorocarbon Tracers in the Atmosphere

A sensitive and selective technique for the quantitative measurement of atmospheric perfluorocarbon trace species at the sub part per quadrillion (10-15) levels is presented. The method utilizes advances in adsorbent enrichment techniques coupled with benchtop capillary gas chromatography and negative ion-chemical ionization mass spectrometry. The development and enhancement of sampling technology for tracer experiments is described, and the results from background measurements and a preliminary field experiment are presented. The overall precision of the analytical method with respect to the preferred tracer for these atmospheric transport studies, perfluoromethylcyclohexane, was ±1.7%. The background concentrations of perfluorodimethylcyclobutane, perfluoromethylcyclopentane, and perfluoromethylcyclohexane at a remote coastal location (Mace Head, Ireland, 53degree N, 10degree W) were found to be 2.5 (±0.4), 6.8 (±1.0), and 5.2 fL L-1 (±1.3), respectively. Background concentrations within an urban conurbation (Bristol, U.K.) were slightly greater at 3.0 (±1.5), 8.1 (±1.8), and 6.3 fL L-1 (±1.1), respectively.