Development of solvent extraction-gas chromatographic method for the identification and determination of polycyclic aromatic hydrocarbons and some related compounds in metallurgical factories
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Date
1991.
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Abstract
A method for the determination of polycyclic aromatic hydrocarbons (PAH) in carbonaceous materials and on particulate Batter produced in the atmosphere during the electrolytic reduction by various methods in the metallurgical industry is presented.
The PAH are extracted into hexane with the aid of ultrasound, which is shown to be more efficient than the conventional Soxhlet thimble technique.
Cyclohexane and hexane are shown to be more selective extractants for PAH than benzene or acetone. Hexane is preferred because it has a lower boiling point than cyclohexane.
Three metnods of identification were investigated. These included thin-layer chromatography (TLCJ, gas chromatography (GO using retention times and indices and mass spectrometry (GC-MS).
Hexane containing 2 % by volume of N.N -dimethylformaoide was used for the development of a thin-layer chromatograa. This resolved only ten of the twenty PAH investigated adequately.
The non-polar OV-101 capillary column used in the GC-MS work did not resolve ten PAH well enough and the mass spectra did not assist in distinguishing overlapping peaks.
The separation of individual PAH was optimised using a DB-5 wall-coated open tubular (WCOT) capillary column coupled to a flame ionisation detector. A splitless injection technique was used.
Calculated retention indices normalised against four selected PAH. viz. naphthalene, phenanthrene. 1,2-benzophenanthrene and 1.2.6.7-dibenzan-thracene were used for the identification of unknown PAH and some related compounds. Problems encountered with this method of identification of some of the more strongly retained PAH are discussed.
The program supplied by "DAPA Scientific (Pty) Ltd." was adapted for quantification of the identified PAH using 1.3,5-triphenylbenzene as internal standard.
Suggestions for the adaption of the above analytical method to different matrices are presented.
Description
A dissertation submitted to the Faculty of Science at the University of Zululand in partial fulfilment for the degree of Master of Science in the Department of Chemistry, 1991.
Keywords
Polycyclic aromatic hydrocarbons, Chromatographic analysis, Metallurgical plants