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Characterisation of Crevice and Pit Solution Chemistries Using Capillary Electrophoresis with Contactless Conductivity Detector
National Centre for Advanced Tribology at Southampton (nCATS), Faculty of Engineering and the Environment, University of Southampton, Southampton SO17 1BJ, UK
Electronics and Computer Science, Faculty of Physical Sciences and Engineering, University of Southampton, Southampton SO17 1BJ, UK
Physical Sciences Department, Defence Science and Technology Laboratory (Dstl), Porton Down, Salisbury SP4 0JQ, UK
* Author to whom correspondence should be addressed.
Received: 4 July 2013; in revised form: 18 September 2013 / Accepted: 23 September 2013 / Published: 30 September 2013
Abstract: The ability to predict structural degradation in-service is often limited by a lack of understanding of the evolving chemical species occurring within a range of different microenvironments associated with corrosion sites. Capillary electrophoresis (CE) is capable of analysing nanolitre solution volumes with widely disparate concentrations of ionic species, thereby producing accurate and reliable results for the analysis of the chemical compositions found within microenvironment corrosion solutions, such as those found at crevice and pit corrosion sites. In this study, CE with contactless conductivity detection (CCD) has been used to characterize pitting and crevice corrosion solution chemistries for the first time. By using the capillary electrophoresis with contactless conductivity detection (CE-CCD) system, direct and simultaneous detection of seven metal cations (Cu2+, Ni2+, Fe3+, Fe2+, Cr3+, Mn2+, and Al3+) and chloride anions was achieved with a buffer solution of 10 mM 2,6-pyridinedicarboxylic acid and 0.5 mM cetyltrimethylammonium hydroxide at pH 4 using a pre-column complexation method. The detection limits obtained for the metal cations and chloride anions were 100 and 10 ppb, respectively. The CE-CCD methodology has been demonstrated to be a versatile technique capable of speciation and quantifying the ionic species generated within artificial pit (a pencil electrode) and crevice corrosion geometries for carbon steels and nickel-aluminium bronze, thus allowing the evolution of the solution chemistry to be assessed with time and the identification of the key corrosion analyte targets for structural health monitoring.
Keywords: structural health monitoring; corrosion solution chemistries; corrosion monitoring; capillary electrophoresis; contactless conductivity detection
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Nie, M.; Wharton, J.A.; Cranny, A.; Harris, N.R.; Wood, R.J.; Stokes, K.R. Characterisation of Crevice and Pit Solution Chemistries Using Capillary Electrophoresis with Contactless Conductivity Detector. Materials 2013, 6, 4345-4360.
Nie M, Wharton JA, Cranny A, Harris NR, Wood RJ, Stokes KR. Characterisation of Crevice and Pit Solution Chemistries Using Capillary Electrophoresis with Contactless Conductivity Detector. Materials. 2013; 6(10):4345-4360.
Nie, Mengyan; Wharton, Julian A.; Cranny, Andy; Harris, Nick R.; Wood, Robert J.; Stokes, Keith R. 2013. "Characterisation of Crevice and Pit Solution Chemistries Using Capillary Electrophoresis with Contactless Conductivity Detector." Materials 6, no. 10: 4345-4360.