Polysorbates are a class of emulsifiers used in some pharmaceuticals and food preparation. They are often used in cosmetics to solubilize essential oils into water-based products. Polysorbates are oily liquids derived from PEG-ylated sorbitan (a derivative of sorbitol) esterified with fatty acids. Surfactants that are esters of plain (non-PEG-ylated) sorbitan with fatty acids are usually referred to by the name Span. It is often required to quantitate Polysorbate (Polysorbate/Tween 20, Polysorbate/Tween 40, Polysorbate 60/Tween 60 and Polysorbate 80) by HPLC in various formulations. Polysorbates exist in form of oligomers.
Barium ion and citric acid are analyzed in the presence of sucrose and Tween 80 on Obelisc N HILIC mixed-mode column. Both compounds are retained in ion-exchange mode and HILIC is not employed with this method. Obelisc N HPLC column has basic and acidic ion-exchange groups separated by long hydrophilic chain. Presence of that long chain allows both cation- and anion-exchange mechanisms to exist simultaneously. Obelisc N column can be used for analysis of cation and anions in HILIC/ion-exchange mode and in ion-exchange mode. Analytes can be monitored by ELSD/CAD and LC/MS.