Aerosol Electroanalysis by PILSNER: Particle-into-Liquid Sampling for Nanoliter Electrochemical Reactions

Particle-into-liquid
sampling (PILS) has enabled robust quantification
of analytes of interest in aerosol particles. In PILS, the limit of
detection is limited by the factor of particle dilution into the liquid
sampling volume. Thus, much lower limits of detection can be achieved
by decreasing the sampling volume and increasing the surface area-to-volume
ratio of the collection substrate. Unfortunately, few analytical techniques
can realize this miniaturization. Here, we use an ultramicroelectrode
in a microliter or smaller sampling volume to detect redox active
species in aerosols to develop the technique of Particle-into-Liquid
Sampling for Nanoliter Electrochemical Reactions (PILSNER). As a proof-of-concept
to validate this technique, we demonstrate the detection of K4Fe­(CN)6 in aerosol particles (diameter ∼0.1–2
μm) and quantify the electrochemical response. To further explore
the utility of the method to detect environmentally relevant redox
molecules, we show PILSNER can detect 1 ng/m3 airborne
Pb in aerosols. We also demonstrate the feasibility of detecting perfluorooctanesulfonate
(PFOS), a persistent environmental contaminant, using this technique.
PILSNER is shown to represent a significant advancement toward simple
and effective detection of a variety of emerging contaminants with
an easily miniaturizable and tunable electroanalytical platform.