Screening of PAH composition and content in used wooden railway sleepers in Lithuania using gas chromatography-mass spectrometry

Abstract

The protection of wooden railway sleepers by impregnating them with coal tar or creosote has proven to be effective for the long term. However high concentration of toxic polycyclic aromatic hydrocarbons (PAH) exists in coal tar or creosote. The investigation of recycling of used sleepers in large amounts has become of great interest [1]. The screening of PAH in used wooden railway sleepers, treated with coal tar and creosote for their protection against biodegradation, has been made, on the basis of cold extraction and soxhlet extraction of the PAHs using several solvents and their determination by GC-MS/GC-FID. Studies include investigation of conifer tree and fir tree railway sleepers. Investigation has been carried out in order to determine extraction solvent efficiency. Variety of solvents was investigated – methanol, acetonitrile, n-hexane, n-heptane, benzene, toluene. Preliminary studies showed, that benzene appears to be the most efficient solvent in order to extract considerable amount of PAH components from wood matrix. Several PAHs were identified naphthalene, acenaphthene, fluorene, anthracene, phenanthrene, fluoranthene, pyrene, crysene, benzo[c]phenanthrene. The concentration range of identified PAHs in the extracts was between 3µg/ml and 200µg/ml.