Anastasova, S.

Bobacka, J.

Diamond, D.

Lewenstam, A.

Paczosa-Bator, B.

Radu, A.

Name not available

Supplementary Material (ESI) for Analytical Methods 
This journal is (c) The Royal Society of Chemistry 2010 
Diagnostic of functionality of polymer membrane – based ion selective electrodes by 
impedance spectroscopy  
C0AY00249F 
 
Figure S1. Response of LCISE upon inflicting a slight physical damage on the membrane. 
Arrows point at the addition of aliquots of standard solution to make the noted sample 
concentration.  
 
Water layer test 
The electrodes were first immersed in a solution of 10-3 M Pb(NO3)2 and the potential was 
followed to stabilize for four hours. The electrodes were then transferred in 10-3 M NaCl and 
the potential monitored overnight. The electrodes were then re-immersed in 10-3 M Pb(NO3)2 
and the potential was monitored for a further four hours. It should be noted that pH of 10-3 M 
Pb(NO3)2 and 10-3 M NaCl solutions were 4.6 and 7.2. Considering selectivity coefficients of 
Pb IV ionophore to Na+ and H+ of 1 and 1 respectively, effect of 
pH of the used solutions is negligible. 
 
Supplementary Material (ESI) for Analytical Methods 
This journal is (c) The Royal Society of Chemistry 2010 
 
Figure S2. Responses of electrodes A (POT-based) and B (without conductive polymer) 
while testing for the presence of water layer between the ion-selective membrane and solid 
support. Strong drifts in the case of electrode B indicate the existence of the water layer. 
 
Calculation of theoretically expected limit of detection 
Equation used for predicting limit of detection (LOD) is developed elsewhere.1 
       (SEq1) 
Under these experimental conditions and assuming that ion fluxes originate only from ion 
exchange at the sample/membrane phase boundary, a detection limit of aPb = 6.3x10-9 M was 
predicted, using the following values; 
 selectivity coefficient for protons logKpotPb,H = -3.5 1, RT (the total amount of ionic sites in 
the membrane) = 0.005 mol/kg, pH = 4.0 (proton activity of aH = 1x10-4 M) and q = 0.0001, 
The parameter q is expressed as:  
           (SEq2) 
Supplementary Material (ESI) for Analytical Methods 
This journal is (c) The Royal Society of Chemistry 2010 
where D and d are the diffusion coefficients and diffusion layer thicknesses of the organic 
(org) and aqueous (aq) phases, respectively. The parameter q was estimated using the 
diffusion coefficient of lead in water (1.35x10-5 cm2/s) 2, the diffusion coefficient of primary 
ion-ionophore complex in the membrane (1x10-8 cm2/s) 3 and a ten-fold smaller thicknesses 
of the aqueous compared to organic layer, which is a reasonable assumption based on a fast 
stirring rate 4.   
 
 
Figure S3. Time traces of Pb2+-selective electrode exposed to bacteria-rich water for four 
days (electrode #8 from Table 1 in main document)). 
 
Supplementary Material (ESI) for Analytical Methods 
This journal is (c) The Royal Society of Chemistry 2010 
LITERATURE 
(1) Ceresa, A.; Bakker, E.; Hattendorf, B.; Gunther, D.; Pretsch, E. Anal. Chem. 2001, 73, 
343-351. 
(2) Valente, A. J. M.; Ribeiro, A. C. F.; Lobo, V. M. M.; Jimenez, A. Journal of 
Molecular Liquids 2004, 111, 33-38. 
(3) Puntener, M.; Fibbioli, M.; Bakker, E.; Pretsch, E. Electroanalysis 2002, 14, 1329-
1338. 
(4) Radu, A.; Peper, S.; Bakker, E.; Diamond, D. Electroanalysis 2007, 19, 144-154. 
 
 


Diagnostic of functionality of polymermembrane–based ion selective electrodes by impedance spectroscopy

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Diagnostic of functionality of polymermembrane–based ion selective electrodes by impedance spectroscopy

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