Determination of fluoride in cement and related materials

This paper describes the determination of fluoride in cement and cement-related materials using a fluoride ion selective electrode. Different sample preparation methods and complexing buffers were investigated. It was concluded that the fluoride electrode offers a rapid and accurate method for fluoride determination in cement and cement-related materials when a suitable buffer medium capable of complexing Si, Al, and Fe in the solution is used. Sintering with Na₂CO₃6ZnO is preferable to LiBO₂ fusion for decomposing materials high in SiO₂, Al₂O₃ and Fe₂O₃. However, the latter method is more rapid and gives the same results as the former method for samples with relatively low SiO₂, Al₂O₃ and Fe₂O₃ contents.