Quantitative matrix isolation Fourier transform spectroscopy of polycylic aromatic hydrocarbons

The utility of matrix isolation Fourier transform infrared spectroscopy (MI FTIR) for the qualitative and quantitative analysis of isomeric polycyclic aromatic hydrocarbons (PAH's) was demonstrated. MI FTIR spectra of sixteen methylated and ten hydrogenated PAH's were obtained.

In order to obtain the spectra of the PAH's, samples were vaporized and codeposited with an excess amount of nitrogen onto an infrared transmitting surface (CsI) which had been cooled to 15K. A cryogenic cell was designed and constructed for obtaining spectra of volatile compounds.

Annealing studies were performed in order to investigate the utility of the technique for quantitative analysis; however, it was determined that annealing was not advantageous in quantitative analysis. The use of peak heights versus peak areas for quantitation was investigated. Although it was determined that either method could be used, the use of peak heights was chosen for the quantitation of compounds in order to minimize precision errors. Experiments were performed to illustrate the increase in precision gained from the use of internal standards. Two PAH's, pyrene and triphenylene, were identified as suitable internal standards.

MI FTIR was utilized in the qualitative and quantitative determination of the PAH content of "real samples." Four components of a synthetic standard were identified and quantitated. The error in the accuracy of the data was less than 12 percent. Pyrene was

vi identified and quantitated in a shale oil fraction which had been separated by gel permeation. Five components of a coking plant effluent sediment sample, which was known to contain at least twenty PAH's, were identified and quantitated. Six additional compounds were tentatively identified in this sample.