Identification of 7-9 ring polycyclic aromatic hydrocarbons in coals and petrol coke using High performance liquid chromatography – Diode array detection coupled to Atmospheric pressure laser ionization – Mass spectrometry (HPLC-DAD-APLI-MS)

Thiäner JB, Nett L, Zhou S, Preibisch Y, Hollert H, Achten C

Abstract

Polycyclic aromatic hydrocarbons containing at least 24 carbon atoms (≥C24-PAH) are often associated with pyrogenic processes such as combustion of fuel, wood and coal and occur in the environment in diesel particulate matter, black carbon and coal tar. Some of the ≥C24-PAH, particularly the group of dibenzopyrenes (five isomers, six aromatic rings) are known to show high mutagenic and carcinogenic activita. Gas chromatography – mass spectrometry is a well-established method for the analysis of lower molecular PAH but is not optimally suited for the analysis of ≥C24-PAH due to their low vapor pressures. Also, hundreds of ≥C24-PAH isomers are possible but only a few compounds are commercially available as reference standards. Therefore, in this study, a combination of multidimensional liquid chromatography, UV diode array detection, PAH selective and highly sensitive atmospheric pressure laser ionization – mass spectrometry is used to detect and unequivocally identify PAH. For identification of PAH in two bituminous coals and one petrol coke sample, unique and compound specific UV spectra were acquired. It was possible to identify ten compounds (naphtho[1,2,3,4-ghi]perylene, dibenzo[b,ghi]perylene, dibenzo[e,ghi]perylene, dibenzo[cd,lm]perylene, benzo[a]coronene, phenanthrol[5,4,3,2-abcde]perylene, benzo[ghi]naphtho[8,1,2-bcd]perylene, benzo[pqr]naphtho[8,1,2-bcd]perylene, naphtho[8,1,2-abc]coronene and tribenzo[e,ghi,k]perylene) by comparison of acquired spectra with spectra from literature. Additionally, it was possible to detect similar distribution patterns in different samples and signals related to alkylated naphthopyrenes, naphthofluoranthenes or dibenzopyrenes. Subsequent effect-directed analysis of a bituminous coal sample using the microEROD (ethoxyresorufin-O-deethylase) bioassay showed high suitability and revealed low EROD induction for the ≥C24-PAH (TEQ range 0.67 -10.07 ng/g) but high EROD induction for the allover