Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 2, pp. 192−199.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © Yu.E. Ermolenko, D.S. Kalyagin, S.N. Subbotina, V.V. Kolodnikov, Yu.G. Vlasov, 2013, published in Zhurnal Prikladnoi Khimii,
2013, Vol. 86, No. 2, pp. 209−216.
AND CORROSION PROTECTION OF METALS
Thallium-Selective Sensor with a Membrane
Based on Tl
Yu. E. Ermolenko, D. S. Kalyagin, S. N. Subbotina,
V. V. Kolodnikov, and Yu. G. Vlasov
St. Petersburg State University, St. Petersburg, Russia
Received October 24, 2012
solid electrolyte with a high ionic component of conductivity was synthesized for develop-
ing a thallium-sensitive sensor. The main sensor characteristics (tilt angle, detection limit, selectivity, pH range,
potential drift) of the new thallium sensor were determined. The time stability of its operation and various ways
of its application for determining thallium ions in solutions are demonstrated.
Thallium and its compounds are widely used for
solving various applied problems. It should be taken into
account that thallium belongs to the group of particularly
toxic microelements, such as cadmium, lead, mercury,
beryllium, barium, and bismuth . The biological
role of many of these, including thallium, is still not
quite clear. The toxicity of thallium is several orders
of magnitude higher than that of mercury; in enzymes
and protoplasm, the thallium ion replaces potassium
to their close ionic radii. Hence follows necessity for
thallium concentration monitoring both in objects
containing thallium and subjected to a technogenic
impact with human involvement and directly in the
human organism. The most sensitive and convenient
technique for analyzing the content of thallium in a
human organism (blood, urine) is mass spectrometry
with inductively coupled plasma , whereas a simpler,
economic, and rapid, even though les sensitive, method
of chemical sensors can be used for determining thallium
in environmental objects.
At present, a large number of various chemical
sensors and their application methods are known (single
sensors, sensor systems of the “electronic tongue”
type, etc.) . Chemical sensors with solid inorganic
membranes can be regarded as the most stable in
operation, which can be fabricated both as conventional
ion-selective electrodes and as microelectronic sensors
of the ISFET type (ion-selective ﬁ eld-effect transistors).
Analytical characteristics of sensors of this kind depend
on the solid-state properties of the membranes used
(ionic and electronic conductivity, carrier concentration
and mobility, solubility, etc.).
The goal of this study was to fabricate and examine
a thallium-sensitive sensor based on the Tl
electrolyte whose main solid-state characteristics have
been analyzed previously . It was found that the high
ionic conductivity due to the mobility of the thallium
ion makes it promising for being used in membranes of
a thallium-selective sensor. Despite the large number of
studies devoted to development of sensors for thallium
ions, no solid-state sensors of this kind have been
reported in the literature.
Among the already known thallium-selective sen-
sors, the following can be noted.
In , poly(vinyl chloride) membrane electrodes
with high selectivity toward Tl
, based on tetrasulfur
macrorings, were suggested. These electrodes have
a Nernst function with a slope of 58.2 mV/decade for
ions with concentrations in the range from 1 × 10
to 2 × 10
M and a detection limit of 1.5 × 10