Unravelling the polysorbate 20 composition: A fusion of UPLC-MS analysis and stochastic modelling

Polysorbate 20 (PS20) is one of the most commonly used non-ionic surfactants in cosmetics, pharmaceuticals and food products. Considered as biocompatible and non-irritating, it is further valued for its solubilising and protein stabilising properties. PS20 is manufactured through a multi-stage reaction of sorbitol with various fatty acids and ethylene oxide, resulting in a complex mixture of components with different molecular weights and polarity. Since variations in the distribution of these components can influence its performance, such as the emulsifying or solubilising efficiency, a detailed understanding of the PS20 composition is of importance. Herein we introduce a combined approach of reversed-phase chromatography with mass detection and automated stochastic modelling that enables the quantitative characterisation of PS20 at the component level. With two straightforward sample preparations and two methods for an ultra-high performance liquid chromatography (UPLC) system coupled to a single quadrupole mass (QDa) detector, this technique ensures efficient data acquisition. Seven PS20 products of different manufacturers, age and qualities were studied using the presented approach. Molar contents and weight percentages were calculated for each of the more than 27'700 components of the PS20, which were fully characterised by i) the substance class (i.e. sorbitan, isosorbide or polyoxyethylene (POE)), ii) the number of esters, iii) the fatty acid combination and iv) the number of OE units. The obtained results allowed not only an accurate prediction of bulk parameters, such as hydroxyl and saponification values, but also a detailed product comparison.