Operating conditions for the qualitative and quantitative determination of fatty acids and several phosphono-fatty acids were investigated by capillary-tube isotachophoresis using a potential gradient detector.
Behenoic acid-NaOH (or Na-behenoate, or K-behenoate) in methanol as a terminal electrolyte and HCl-Tris in methanol as a leading electrolyte were effective for analysis of fatty acids. The potential unit (PU) values for capillary-tube isotachophoresis depended on the molecular weight of fatty acids. The isotachophoretic sensitivities of fatty acids decreased with increasing carbon chain length of the fatty acids.
Isotachophoregrams of phosphono fatty acids showed only one zone coresponding to the secondary dissociated ion species. The results regarding phosphono-fatty acids are discussed in terms of charge.