Quadrupole mass spectrometer operating in the electron-capture negative ion mode as detector for comprehensive two-dimensional gas chromatography

A recently introduced rapid-scanning quadrupole mass spectrometer (qMS) with an electron-capture negative ion (ECNI) option, the Perkin-Elmer Clarus 500, was tested as a detector for comprehensive two-dimensional gas chromatography (GC × GC). The parameters influencing the data acquisition rate in the scan mode, such as scan time and inter-scan delay, and in the selected ion monitoring mode, such as dwell time and inter-channel delay, were evaluated. In the scan mode, good-quality mass spectra covering a range of 300 Da can be obtained at an acquisition rate of 23 Hz; in selected ion monitoring, an acquisition rate of 90 Hz can be achieved when monitoring a single ion. Compared with electron ionisation, the use of electron-capture negative ionisation causes no extra peak broadening. As applications, mixtures of polychlorinated n-alkanes (PCAs), polybrominated diphenyl ethers (PBDEs) and polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were analysed. The separation of PCAs based on their number of chlorine substituents was confirmed for the first time by using GC × GC-ECNI qMS in the scan mode and a significantly improved limit of detection was achieved for BDEs (10-150 fg injected) and CDD/Fs (10-700 fg injected) in the selected ion monitoring mode

Trace level analysis of micropollutants in aqueous samples using gas chromatography with on-line sample enrichment and large volume injection.

In this review article an overview of methods for the analysis of aqueous samples with capillary gas chromatography is presented. The methods can be classified into two approaches: a direct approach in which water is directly introduced onto the GC column, and an indirect approach in which water is eliminated, i.e., by liquid-liquid extraction or solid-phase extraction, prior to introduction of the analytes onto the GC column. The emphasis is on methods in which sample preparation and GC analysis are combined on-line. An outline of methods for large volume injection is also presented as the use of on-line systems often involves the introduction of large volumes of sample extract