Screen-printed gold electrodes as passive samplers and voltammetric platforms for the determination of gaseous elemental mercury

 We present a novel methodology for the determination of gaseous elemental mercury (GEM). It is based on passive sampling of Hg on screen-printed gold electrodes (SPGEs), followed by measurement of the amalgamated mercury by square wave anodic stripping voltammetry (SWASV). We have explored in detail the behaviour of the SPGE electrode surface during the sampling process (by applying Time Of Flight Secondary Ions Mass Spectrometer, TOF-SIMS), the stability of the voltammetric signals and the inter-electrode reproducibility, with acceptable results. The adsorption of mercury on the SPGE follows a nearly linear behaviour until the sorbent becomes saturated (equilibrium phase) for different mercury concentrations, allowing to select a sampling time of 30 minutes for calibration. The theoretical behaviour of the sampling system was modelled, considering the changes in the diffusive path length between the porous diffusive barrier and the absorption surface, . Finally, we have tested two GEM calibration protocols. The first one is based on the measurement of mercury stripping peak area, AHg, and the second one is based on the measurement of the mass of mercury, mHg, by standard additions. We found good correlation coefficients between the GEM concentration for both  (R² = 0.9591) and   (R² = 9615) in the range from 5.82 to 59.29 ng dm^-3 of GEM. Detection limits were 5.32 and 5.22 ng dm^-3 for AHg and mHg , respectively. Our results open a new line of electroanalytical strategies for the determination of gaseous elemental mercury in atmospheric samples.

Read the full text at: https://dx.doi.org/10.1021/acs.analchem.0c04347