Analysis of polysorbate and its polyoxyethylated metabolite

Polysorbates are used as emulsifiers in a number of pharmaceuticals and have been implicated as the possible toxic agent in the neonatal vitamin supplement, E-Ferol. In the investigation of the toxicity of this compound, it was necessary to find a method to separate and quantitate polysorbate and its polyoxyethylated metabolite from biological fluids. A high-performance liquid chromatography method was developed which combines the use of a 500 A mu Styragel size exclusion column with an ammonium cobaltothiocyanate complexation column and detection at 620 or 320 nm. The detection limit is approximately 5 micrograms. The method was used to demonstrate that polysorbate was metabolized in vitro by hepatocytes and that the urinary metabolite in humans is comparable to that produced by the rat.