PERFORMANCE-CHARACTERISTICS OF A REAL-TIME DIRECT DEPOSITION GAS-CHROMATOGRAPHY FOURIER-TRANSFORM INFRARED SPECTROMETRY SYSTEM

In this paper, the real-time measurement of the infrared spectra of subnanogram quantities of anatytes that have been separated by gas chromatography (GC) Is demonstrated for the first time. Eluites trapped as small spots on a moving window held at 77 K are passed through the beam of a Fourier transform Infrared (FT-IR) spectrometer that Is 100 μm square. Real-time GC/FT-IR spectra obtained from injected quantities as low as 50 pg are shown and the effect of postrun signal-averaging in improving the signal-to-noise ratio is demonstrated. With this technique, subnanogram quantities of n-alkanes at least up to C22H45 can be discriminated. Identification of polar, hydrogen-bonded anatytes is accompolished by spectral searching against standard libraries of compounds prepared as KBr disks. For less polar analytes, spectral searching against a database of vapor-phase spectra is also successful. © 1990, American Chemical Society. All rights reserved.