Determination of the main bioaerosol components using chemical markers by liquid chromatography–tandem mass spectrometry

This work is part of an extensive research project aimed at the determination and characterization of bioaerosol with a multidisciplinary approach. In this context, one of the main objectives of the project has been the development of a comprehensive analytical method for the determination of different chemical biomarkers of the bioaerosol, by liquid chromatography coupled with tandem mass spectrometry. The following biomarkers have been considered, and correlated to specific components of bioaerosol as unambiguous indicators: • ergosterol fungal components • chlorophylls, phytosterols (stigmasterol and b-sitosterol), -tocoferol vegetable cells and algae • cholesterol animal cells, vegetable cells and algae. • dipicolinic acid bacterial spores • muramic and meso-2,6-diaminopimelic acid bacterial cells To verify the method, to find diagnostic ratios and to calculate the appropriate conversion factors, fungal spores, bacterial cells and spores, and algae of known species, commonly airborne, were analysed. The material was subjected to freezing and de-freezing cycles, followed by extraction, hydrolysis and purification of the biomarkers. The chromatographic separation of the bacterial biomarkers was achieved by using a polymeric column, based on Hydrophilic Liquid Interaction with the electrospray ionization mass spectrometric detection, whereas sterols and chlorophylls were separated by a reversed phase column, coupled to atmospheric pressure chemical ionization – tandem mass spectrometer. The optimized method was applied to environmental particulate matter sampled in an outdoor site. Bacterial and fungal content was compared to the results obtained from the classical direct viable counting method in the sampled particulate matter