Adsorption isotherms of hydrophobic substances onto a chromatographic organic monolith

Adsorption isotherms of hydrophobic substances (methylparaben, coumarin, vanillin, isovanillin, and caffeine) onto a chromatographic organic monolith were measured at 24°C. Adsorption isotherms of coumarin and caffeine were linear and were expressed by the Henry equation. On the other hand, the isotherms of methylparaben, vanillin, and isovanillin were non-linear and could be expressed by combining the Henry and Langmuir equations. Among the adsorbates having almost the same molecular masses, vanillin was adsorbed the most on the organic monolith, and methylparabene followed. The adsorbate hydrophobicity was not a main parameter reflecting the adsorbability, but any specific interaction between the adsorbate and the monolith would play an important role on the absorbability onto the monolith. © 2015, Japan Society for Food Engineering. All rights reserved.