Rapid Identification of Aliphatic Ketones from Vapor-Phase Infrared Spectra

Computerized interpretation of vapor phase infrared spectra using a pattern search for spectra/structure correlation for vapor phase spectra is introduced. Rapid identification of aliphatic ketones in gaseous mixture can be achieved using this pattern search. This new approach of interpretation of infrared data based on the average pattern of infrared spectra has potential for rapid identification of the components of the complex mixture samples. The methods can also be used in generating vapor-phase infrared spectra/structure correlation rules to obtain a better understanding of the correlation. The need for the identification of compounds present in complex gaseous mixture or after separation by gas chromatography (GC) using vapor-phase infrared (VPIR) spectrometry is becoming increasingly important. This is primarily due to advances in Fourier transform infrared (FTIR) spectrometry allowing the acquisition of complete spectra in a few tenths of a second with detection limits of less than 1 ppb in long path infrared gas cells and below 10 nanogarms in the GC/FT-IR interface. With a GC/FT-IR system hundreds of spectra can be generated per chromatogram. Clearly, the limiting processes are the spectral searching and, in cases where the search results are ambiguous, spectral interpretation steps. A powerful digital computer is needed to control the interferometer and perform the Fourier transformation from the time domain to the frequency domain in order to obtain the spectrum. This makes the incorporation of automatic spectral interpretation in the same computer an obvious and sensible capability. It should be kept in mind that the ultimate goal of the chemist is not simply to produce a collection of spectra but rather to determine what chemical compounds are present in the unknown samples and what their significance is to the problem at hand