Potentiometric Detection of Model Bioaerosol Particles

Abstract

A new technique for the detection of bioaerosols is presented, utilizing particle combustion/ionization in a premixed hydrogen/oxygen/nitrogen flame plasma, followed by gas phase electrochemical detection. Bermuda grass pollen (Cynodon dactylon, one of the most common causes of pollen allergy) and black walnut pollen (Juglans nigra) were used as model bioaerosol particles. We demonstrate that single particle detection can be comfortably achieved by zero current potential measurements between two platinum electrodes, giving potential signals of over 800 mV and unique fragmentation features which may be used for differentiating between species. The high sensitivity is due to the inherent amplification through flame fragmentation, gasification and ionization; a single pollen grain of 25 μm diameter can give a plume of combustion products measuring 4 mm in diameter. The physical basis of the potential difference is a mixed interfacial potential with an additive diffusion/junction potential due to the increase in ionization from the pollen combustion. The results suggest this methodology may be applied to the detection of particulates composed of ionizable species (organic or inorganic) in gaseous environments, such as bacteria, viruses, pollen grains, and dust. Its effectiveness will depend on the propensity of the target particle to combust and generate voltages under specific flame and electrode conditions.

Primary biological aerosol particles in the atmosphere: a review

“…Lee et al, 2008;Seshadri et al, 2009;Yoon et al, 2010). Electrochemical, immunochemical and immune biological methods have also been investigated for ambient PBAP characterisation (Rishpon et al, 1992;Spurny, 1994;Sarantaridis and Caruana, 2010;Schmidt and Bauer, 2010). It should be noted here that complementary instruments such as biological aerosol particle concentrators have also helped enable analyses by a variety of instruments (e.g.…”

“…Laserinduced breakdown spectroscopy (LIBS) has easily been the most common form of BS method and has been employed to characterise pollen (Boyain-Goitia et al, 2003), and fungal spores (Hybl et al, 2003), bacteria (Morel et al, 2003) and a variety of biological aerosol particle types (Samuels et al, 2003). Other forms of elemental analysis such as spark-induced breakdown spectroscopy (SIBS), particle-induced X-ray emission (PIXE) and various forms of combustion analysis have also been utilised for laboratory study of biological aerosol (Sarantaridis and Caruana, 2010;Schmidt and Bauer, 2010).…”

Bioaerosol detection using potentiometric tomography in flames

“…The physical origin of this potential difference was discussed at length in ref. 26. In that work we recognised that the potential is mainly due to a diffusion potential established between the indicator and ground electrode.…”

“…More details of the setup can be found in ref. 26. For this study 6 different flame compositions were used as shown in pollen due to its easier aerosolisation at our lab conditions.…”

“…In previous work we described plasma electrochemical detection at single pole electrodes as a basis of detection of single bioaerosol fragmentation. [26][27][28] In this work we describe a novel approach to image the combustion plume produced by a single pollen particle as it passes through the plane of a set of precisely positioned electrodes, represented schematically in Fig. 1.…”