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PVC MATRX IONIC - SURFACTANT SELECTIVE ELECTRODES BASED ON THE IONIC PAIR… We purified the ionic association compound by washing the precipitate with small amounts of water on the filter or by washing the extract in the organic solvent with distilled water several times (negative reaction with AgNO3). The ionic association compound obtained may contain traces of water that can be removed by treating with anhydrous sodium sulfate, after dissolving in acetone. CTMA-LS has been obtained based on the information found in literature regarding the preparation of ionic association compounds [17,19]. We mixed hot 10 mL of NaLS 0.05 M solution with the same volume of CTMA-Br 0.05 M solution, stirring continuously. A white precipitate of CTMA-LS was obtained, that was purified and desiccated according to the method presented above. The ionic association between the laurylsulphate anion and the tricaprylmethylammonium cation was obtained by mixing together 50 mL NaLS 0.05 M solution with 50 mL TCMA-Cl equimolar solution. The mixture of the two solutions was agitated for 15 minutes on water bath at 60°C. From the white emulsion obtained was extracted the TCMA-LS using chloroform and then it was purified and desiccated. The TCMA-LS obtained has a semisolid state. Preparation of the membrane From the point of view of the composition, the classical procedure has been used, with 1% ionophore, 33% PVC and 66% plasticizer [17,19-20]. We have used as ionophores: the ionic association compounds: CTMA-LS and TCMA-LS. As plasticizers we have used TCF, o-NPOE and DOS. The polymeric membrane has been prepared by dissolving its components in tetrahydrofurane in the following order: ionophore, PVC and plasticizer. We poured a few drops of the resulting solution on the surface of the metallic plate of the electrode. After the slow evaporation of the solvent (enclosed recipient) on the metallic surface remains the polymeric membrane sensible to anions, well attached to the PVC body of the electrode. In order to raise the calibration curve, the electrodes were conditioned by maintaining them in a NaLS 10 -2 M solution for 24 hours. When not used, the electrodes should be stored dry, in dark places. They should be reconditioned by washing with HCl 5x10 -3 M solution for 30 minutes and then by magnetic stirring in a NaLS 10 -4 M solution before use. Construction of the electrode The technology for producing the “all solid state” sensors consists in forming the sensible PVC membrane directly on the metallic support, attaching it to the PVC electrode body. 149
150 CRISTINA MIHALI, GABRIELA OPREA, ELENA CICAL The electrode is made of a PVC body with a copper or silver plate tightly attached at its bottom, which has attached the copper wire of the coaxial cable for coupling to the measuring device. On the plate surface there is the polymeric membrane which contains the ionophore and the plasticizer. This layout of the electrode has the great advantage of a solid internal contact because it does not require internal reference electrode and internal electrolyte. REFERENCES 1. D. O. Hummel, Analyse der Tenside, Carl Hansen Verlag, München, Wien, 1995, chapters 4-5. 2. M. Gerlache, J. M. Kauffmann, G. Quarin, J. C. Vire, G. A. Bryant, J. M. Talbot, Talanta, 1996, 43, 507. 3. J. Sanchez, Critical Reviews in Analytical Chemistry, 2005, 35, 15. 4. P. Săp, D. F. Anghel, C. Luca, Rev. Roum. Chim., 1983, 28, 883. 5. W. Szczepaniak, M. Ren, Electroanalysis, 1994, 6, 341. 6. L. Campanella, F. Mazzei, M. Tomassetti, R. Sbrilli, Analyst, 1988, 113, 327. 7. W. Szczepaniak, Analyst, 1990, 115, 1451. 8. J. Baró Romá, J. Sánchez, M, del Valle, J. Alonso, J. Bartroli, Sensors and Actuators B, 1993, 15-16, 179. 9. R. Matesic-Puac, B. Sak-Bosnar, M. Bilic, B.S. Grabaric, Sensors and Actuators B, 2005, 106, 221. 10. N. M. Mikhaleva, E. G Kulapina,. Electroanalysis, 2006, 13-14, 1389. 11. J. Sancez, M. del Valle, Talanta, 2001, 54, 893. 12. T. Masadome, S. Kugoh, M. Ishikawa, E. Kawano, S. Wakida, Sensors and Actuators B, 2005, 108, 888. 13. J. Vessel, K. Tulip, ˝Analysis with ion-selective electrodes˝, Ellis Horwood Ltd., Chichester, 1978, chapter 2. 14. S. Alegret, J. Alonso, J. Bartroli, J. Baró-Romà, J. Sánchez, Analyst, 1994, 119, 2319. 15. E. Chifu, 2000, ˝Chimia coloizilor şi a interfeţelor (˝The colloid and interfaces chemistry˝), Ed. Presa Universitară Clujeană, Cluj-Napoca, 2000, chapter 3. 16. D. Mihai, R. von Klitzing, D. F. Anghel, 11 th Physical Chemistry Conference with International Participation ROMPHYSCHEM 11, Timişoara, Romania, 2003. 17. M. Gerlache, Z. Sentürk, J. C. Viré, J. M. Kauffmann, Anal. Chim. Acta, 1997, 349, 59. 18. N. Buschmann, H. Strap, Tenside Surf. Det., 1997, 34, 84. 19. B. Kovács, B. Csóka, G. Nagy, A. Ivaska, Anal. Chim. Acta, 2001, 437, 6. 20. G. J. Moody, J. D. R. Thomas, ˝Selective Ion Sensitive Electrodes˝, Merrow, Watford, 1971, chapter 3.
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R /(mol m -2 s -1 ) 0.06 0.05 0.04
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ANA-MARIA CORMOS, JOZSEF GASPAR, AN
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Studia Universitatis Babes-Bolyai C
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6 PROFESSOR IOAN BÂLDEA AT HIS 70
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MARCELA ACHIM, DANA MUNTEAN, LAURIA
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STUDIA UNIVERSITATIS BABEŞ-BOLYAI,
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STUDIES ON WO3 THIN FILMS PREPARED
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PREPARATION AND CHARACTERIZATION OF
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34 C. CĂŢĂNAŞ, M. MOGOŞ, D. HO
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MATHEMATICAL MODELING FOR THE CRYST
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STUDY OF THE CHROMATOGRAPHIC RETENT
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LOWER RIM SILYL SUBSTITUTED CALIX[8
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THE INTERACTION OF SILVER NANOPARTI
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THE INTERACTION OF SILVER NANOPARTI
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202 OCTAVIAN STAICU, VALENTIN MUNTE
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EXPERIMENTAL SECTION 210 MARIA ŞTE
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EQUILIBRIUM STUDY ON ADSORPTION PRO
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E / mV vs. SCE POTASSIUM-SELECTIVE
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