Ion chromatographic analysis of amines, alkanolamines, and associated anions in concrete

In order to assess the effectiveness of applying penetrating corrosion inhibitors to the surface of reinforced concrete, it is necessary to devise accurate methods for their detection and quantification. In this paper, methods for ion chromatographic analysis of a variety of amines, alkanolamines, and associated anions, which may be used as corrosion inhibitors for steel reinforcement in concrete, are described. By careful adjustment of the conditions for analysis, these inhibitors were readily identified and quantified in concrete/cement pore solutions or digests. Characterisation of the cationic inhibitors, ethanolamine, quaternary methylammonium, dimethylethanolamine, cyclohexylamine, guanidine, and arginine, and the anionic inhibitors, nitrite, molybdate, acetate, benzoate, and azelate, was carried out conductimetrically. To enhance the sensitivity of detection, amperometry was used for the analysis of triethanolamine and low concentrations of ethanolamine. Ion chromatography was also used as a means of obtaining a distribution profile of the concentrations of inhibitor ions present throughout a concrete structure.