Quantification of calcium alginate gel formation during ionic cross-linking by a novel colourimetric technique

Abstract A simple and rapid colourimetric technique using murexide as an indicator to characterise and quantify Ca-alginate gel formation during the treatment of sodium alginate solution using divalent cation (Ca 2+ ) as a cross linking agent has been examined. The change of colour of the gel was characterised in terms of hue angle. The effect of sample size, murexide concentration and alginate concentration on the hue angle and amount of Ca-alginate gel formation was investigated. A linear correlation between the hue angle and the degree of Ca-alginate gel formation was obtained and described in a mathematical equation. This method can be easily applied to other gelation systems by tailoring mathematical equation parameters to a specific particular system.