Characterisation of Crevice and Pit Solution Chemistries Using Capillary Electrophoresis with Contactless Conductivity Detector

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.

Contactless conductivity detection for analytical techniques—Developments from 2012 to 2014

“…Nie et al. reported the use of CE‐C 4 D in the analysis of solutions used in corrosion studies . An important reason for choosing CE‐C 4 D for these applications is its applicability for small sample volumes in the low microliter range.…”

Electrochemical detection of cupric ions with boron-doped diamond electrode for marine corrosion monitoring

“…The nil toxicity, 31 the high overpotentials for oxygen and hydrogen evolutions [8], 32 the high chemical and physical stability in addition to the low 33 capacitive current in aqueous solutions [9], make BDD an attractive 34 electrode material widely used in electroanalysis. One of the most 35 extensively investigated BDD characteristics is the surface 36 property and its influence on the electron transfer process.…”

A five-electrode capacitively coupled contactless conductivity detector with a low limit of detection

“…[6][7][8][9][10][11][12] In addition, C 4 D has the advantages of miniaturization and being nondestructive to samples. Thus it has been widely applied in the elds of environment, 13,14 food, 15,16 medicine [17][18][19] and others.…”