While ion current rectification (ICR) in aprotic solvent
has been
fundamentally studied, its application in sensing devices lacks exploration.
The development of sensors operable in these solvents is highly beneficial
to the chemical industry, where polar aprotic solvents, such as acetonitrile,
are widely used. Currently, this industry relies on the use of inductively
coupled plasma mass spectrometry (ICP-MS) and optical emission spectroscopy
(OES) for the detection of metal contamination in organic products.
Herein, we present the detection of trace amounts of Pd2+ and Co2+ using ion current rectification, in cyclam-functionalized
quartz nanopipettes, with tetraethylammonium tetrafluoroborate (TEATFB)
in MeCN as supporting electrolyte. This methodology is employed to
determine the concentration of Pd in organic products, before and
after purification by Celite filtration and column chromatography,
obtaining comparable results to ICP-MS within minutes and without
complex sample preparation. Finite element simulations are used to
support our experimental findings, which reveal that the formation
of double-junction diodes in the nanopore enables trace detection
of these metals, with a significant response from baseline even at
picomolar concentrations.