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

Abstract

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), α-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.

Evaluation of Bioaerosol Bacterial Components of a Wastewater Treatment Plant Through an Integrate Approach and In Vivo Assessment

“…For chemical analyses, the thirteen filters of the first multistage impactor were re-assembled into two sets that corresponded to particle fraction with Da < 1 µm (particulate matter (PM) < 1) and Da > 1 µm (PM > 1). Sample preparation was extensively detailed in a previous paper [44]. Shortly after sampling, filters were added to 500 µL of deionized water.…”

“…The limit of quantification (LOQ) was estimated in the same way as the LOD-with the use of a criterion (S/N) of 10. All the validation parameters were evaluated in our previous investigation [44].…”

“…Quantitative analyses of microbes were carried out by using matrix calibration curves to bypass eventual signal suppression [53]. Muramic acid was used as a biomarker of bacterial vegetative cells by applying a conversion factor of 0.6%, and dipicolinic acid was used as a biomarker of bacterial spores by applying a conversion factor of 10% [37,44]. Figures 2 and 3 show the number of cells and spores/m 3 , assuming the average weight of a bacterial cell to be 1 pg and of a bacterial spore to be 0.6 pg.…”

Application of DPPH Assay for Assessment of Particulate Matter Reducing Properties

“…In fact, PM is a heterogeneous and complex mixture of particles [25] that varies in composition and it is very difficult to identify the exact chemical constituents [26]. Some studies proved the presence of species with likely antioxidant and reducing characteristics such as phenols from wood burning [27], phenolic compounds from different sources [28], pollen [29], airborne bioaerosols that are biological in origin [30], and biological and vegetable components [31].This research was aimed at clarifying the latter aspect by considering the application of an acellular procedure to evaluate the presence of reducing species in PM samples. The 2,2-diphenyl-1picrylhydrazyl (DPPH) assay is a rapid, simple, and widely used method to evaluate the antioxidant potential of a compound or an extract [32], and it is commonly used for vegetable juice [33], olive oils, and wines [34].…”

“…In fact, PM is a heterogeneous and complex mixture of particles [25] that varies in composition and it is very difficult to identify the exact chemical constituents [26]. Some studies proved the presence of species with likely antioxidant and reducing characteristics such as phenols from wood burning [27], phenolic compounds from different sources [28], pollen [29], airborne bioaerosols that are biological in origin [30], and biological and vegetable components [31].…”