1070-4272/02/7505-0727$27.00C2002 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 75, No. 5, 2002, pp. 727!732. Translated from Zhurnal Prikladnoi Khimii, Vol. 75, No. 5,
2002, pp. 746!751.
Original Russian Text Copyright + 2002 by Makarychev-Mikhailov, Goryacheva, Rudnitskaya, Vlasov.
AND ION-EXCHANGE PROCESSES
Tetraphenylporphyrin Sensors with High Cross Sensitivity
for [Electronic-Tongue] Analyzers
A. V. Legin, S. M. Makarychev-Mikhailov, O. E. Goryacheva,
A. M. Rudnitskaya, and Yu. G. Vlasov
St. Petersburg State University, St. Petersburg, Russia
Received February 1, 2002
Abstract-Tertaphenylporphyrin-based film sensors were prepared with anionic and cationic lipophilic ionic
additives introduced into polyvinyl chloride membranes plasticized with various solvents. The data obtained
with these sensors were used to calculate the parameters of the cross sensitivity of the sensors. A multisensor
system of the [electronic tongue] type was developed on the basis of the sensors studied.
Chemical sensors and sensor systems form a rapid-
ly developing class of analytical instruments with
a wide variety of fields and objects of application.
Porphyrins and their derivatives play increasingly im-
portant part in chemical analysis , with chemical
sensors constituting one of the most important fields
of application of porphyrins and metal porphyrins.
Highly selective electrodes for determining chloride
[2, 3], nitrite [4, 5], thiocyanate , salicylate , and
other anions have been developed on their base. In
view of the specific interaction between metal por-
phyrins and anions, the selectivity of sensors of this
kind markedly differs from the selectivity of sensors
based on classical anion exchangers, quaternary am-
monium salts characterized by the so-called Hof-
meister selectivity series .
At present, active research is also being conducted
in the field of cation-sensitive sensors, in particular,
nickel(II)-sensitive devices [9, 10], on the basis of
porphyrins and related compounds, but the selectivity
of sensors of this kind is poor. Nevertheless, such
sensor materials may be of much interest.
Using a multisensor system of the [electronic
tongue] type, including sensors that are weakly selec-
tive but exhibit high cross sensitivity (CS) to various
solution components [11, 12], one can analyze multi-
component media with complex composition. The re-
sponse of sensors belonging to the system contains
information about many components of the complex
solution; the multidimensional analytical signal gen-
erated in such a system is commonly processed using
modern methods of mathematical statistics, e.g.,
image recognition and multidimensional calibration.
The use of multisensor systems enables quantitative
determination of many ions and other components
whose activity or concentration cannot be determined
by the conventional potentiometric techniques. The
[electronic tongue] enables multicomponent quantita-
tive analysis, with several substances determined in
a complex liquid medium simultaneously. In addition,
multisensor systems can be used to perform integrated
qualitative analysis (identification, recognition, clas-
sification) of various liquid media.
In terms of the [electronic tongue] concept, specif-
ic requirements are imposed upon the sensors, the
main of which is high cross sensitivity understood as
the sensitivity of a sensor material to, simultaneously,
several or many solution components, which are not
necessarily ionic, and high reproducibility of charac-
teristics of the system in operation in complex media.
Previously, parameters for evaluation of the cross
sensitivity and possible ways of search for new sensor
materials have been proposed .
Tetraphenylporphyrin is rather promising mem-
brane-active component (MAC) owing to its ability
to form complexes with numerous cations .
Although some selective sensors on the basis of tetra-
phenylporphyrin have already been reported , the
appearance of a new approach to evaluation of the
sensor sensitivity requires a reconsideration of the
views about the possibilities of many known MACs.
For example, not-too-highly selective sensors exhibit-
ing reproducible cross sensitivity can be successfully
used to create multisensor systems. Polymer film
cation-sensitive sensors based on MAC of varied
nature have been studied previously .