Interfacial tensiometry as a novel methodology for the determination of surfactant adsorption at a liquid surface

At low surfactant concentration the loss of molecules in the bulk phase due to adsorption can be significant if the surface-area-to-bulk-volume ratio is large. This loss of molecules, however, can be used to determine the adsorption of a surfactant if the experiments are performed under well-controlled conditions. Experiments are performed with the model surfactant tridecyldimethylphosphine oxide (C13DMPO) using drop profile analysis and ring tensiometry. Taking into account the different area/volume ratios and the measured equilibrium surface tensions as a measure of the final surfactant bulk concentration, the adsorption of C13DMPO is determined.