Ultraviolet spectrometric detection for gas chromatography of polynuclear aromatic compounds with repetitive spectral scans using absorbance and concurrent fluorescence measurements.

A computer-controlled ultraviolet spectrometric detection system for gas chromatography (GC) is described which acquires absorption spectra of gas-phase GC effluents at rates up to two 62-nm scans per s. Concurrent fluorescence measurements enhance the selectivity of this detection system, providing additional qualitative information. The system has been designed to preserve chromatographic resolution and is selective for aromatic compounds. This multi-mode GC detection is demonstrated through GC separations of polynuclear aromatic compounds with limits of detection ranging from 30 to 70 ng for absorbance measurements. The spectral information obtained with this detection system may be used for compound identification, enhancement of the selectivity and for resolving co-eluting GC eluites.