Application of metalloporphyrin-based acetate-selective electrodes in FIA systems

Monika Mroczkiewicz ,  Mariusz Pietrzak ,  Łukasz Górski ,  Elzbieta Malinowska 

Warsaw University of Technology, Faculty of Chemistry, Noakowskiego 3, Warszawa 00-664, Poland

Abstract

                 Metalloporphyrins emerged recently as particularly interesting ionophore species1. The selectivity pattern of this group of ionophores is significantly different from the sequence based on ions free energy of hydration (so-called Hofmeister selectivity pattern2). It was shown that the unique potentiometric selectivities observed for membranes doped with various metalloporphyrins result from selective interaction of analyte anion with the metal center of the porphyrin structure. Metalloporphyrin – based ISEs could serve as detectors in flow injection analysis (FIA) systems. Example of such system is setup developed for glucose determination with metalloporphyrin-based polymeric-membrane ISE selective to fluoride as a detector3.

Fig. 1. Structure of dichloro[5,10,15,20-tetra(tertbutylphenyl)porphyrinato]zirconium(IV).

               The scope of this work was to study the influence of porphyrin structure and polymer membrane composition on the acetate response of ISEs doped with Zr(IV) – porphyrins. Among few tested ionophores, the best response parameters (selectivity, sensitivity, LDL) towards acetate were obtained for electrodes with membranes containing Zr(IV)-tTPP (see Fig. 1). Electrodes with membranes based on the chosen compound were then used as detectors in FIA systems for acetylcholine determination and acetylcholinesterase inhibition studies.

Fig. 2. FIA measurement setup for acetylcholine determination used in this work.

                The method based on the enzymatic hydrolysis reaction, where choline and acetate are produced, was applied for acetylcholine determination. Enzyme (acetylcholinesterase) was covalently immobilized on amberlite XAD7 and placed in PVC tubing forming flow-through reactor.  Newly designed system (see Fig. 2), is the only one, described in literature to date4, that uses potentiometric detection of acetate for acetylcholine determination.  Proposed FIA system allowed for determination of acetylcholine in the range of 10−4 to 10−1 M, with the throughput of 60 samples per hour. The lifetime of enzymatic reactor was approximately 9 days. The electrode response parameters stayed unchanged during this period.

            The same system was used for determination of chlorpyrifos – the organophosphorus  insecticide compound which can function as inhibitor of acetylcholinesterase, resulting in decrease of acetate-dependent signals. The preliminary studies showed that such system allows for determination of inhibitor compound at the level of 105 M.

1. Ł. Gorski, E. Malinowska, P. Parzuchowski, W. Zhang, M.E. Meyerhoff, Electroanalysis 15 (2003) 1229.

2. F. Hofmeister, Arch. Exp. Pathol. Pharmakol. 24 (1888) 247

3. Ł. Gorski, D. Klimaszewska, M. Pietrzak, E. Malinowska, Anal. Bioanal. Chem. 389 (2007) 533.

4. Ł. Gorski, M. Mroczkiewicz, M. Pietrzak, E. Malinowska, Analytica Chimica Acta 644 (2009) 30–35

Legal notice
  • Legal notice:

    Copyrighted materials, (c) Pielaszek Research, all rights reserved.
    The above materials, including auxiliary resources, are subject to Publisher's copyright and the Author(s) intellectual rights. Without limiting Author(s) rights under respective Copyright Transfer Agreement, no part of the above documents may be reproduced, stored in or introduced into a retrieval or caching system, or transmitted in any form or by any means (electronic, mechanical, photocopying, recording or otherwise), or for any purpose, without the express written permission of Pielaszek Research, the Publisher. Express permission from the Author(s) is required to use the above materials for academic purposes, such as lectures or scientific presentations.
    In every case, proper references including Author(s) name(s) and URL of this webpage: http://science24.com/paper/21893 must be provided.

 

Related papers
  1. Electrochemical uranyl biosensor with DNA oligonucleotides as receptor layer
  2. Metallacarboranes as redox labels in voltammetric methods of DNA determination
  3. Application of mass fabricated silicon-based gold transducers for amperometric (bio)sensors
  4. Solid state potentiometric sensors with gold internal contact

Presentation: Poster at SMCBS'2009 International Workshop, by Monika Mroczkiewicz
See On-line Journal of SMCBS'2009 International Workshop

Submitted: 2009-08-31 15:32
Revised:   2009-08-31 15:42
Google
 
Web science24.com
© 1998-2021 pielaszek research, all rights reserved Powered by the Conference Engine