FOURIER TRANSFORM INFRARED SPECTROMETRY: ENVIRONMENTAL PROBLEM-SOLVING BY COMPUTERIZED TECHNIQUES GC/FTIR, DOMAIN, DATA, STRUCTURE ELUCIDATION).

摘要

Various techniques were devised that can enhance the efficiency and effectiveness of gas chromatography/Fourier transform infrared (GC/FT-IR) systems toward the analysis of complex environmental samples. An improved method for the optimized detection and extraction of eluate peak interferometric data provides near optimum spectral quality in most situations without the necessity of extensive user interaction. This method substantially reduces the time normally required for this operation while improving the results associated with further processing steps.; A peak correlation technique was developed that relates eluate peaks of the same chemical species from different samples on the basis of similarities exhibited by their corresponding interferometric data. This correlation method substantially limits the number of redundant post separation data processing steps for those eluate peaks that have been encountered and identified previously from a similar sample. The method also can confirm the presence of a homologous series and detect coeluting species associated with the same chromatogram.; A detailed examination of the use of Fourier domain rather than absorbance spectral representations of compounds as a means of elucidating the presence of specific structural units was conducted. Through the use of vector methods, the Fourier domain representations of the 3300 member EPA vapor phase infrared library were classified into specific categories according to their inherent similarities. This work allowed the specification of molecular structural units that consistently produced characteristic features in the Fourier domain signals of compounds. The categorization results provided the basis for the development of an extremely rapid infrared data interpretation algorithm. The effectiveness of this technique in providing valid structural suggestions for compounds not represented in the spectral library was demonstrated.