Quantitative determination of polysorbate to in non-standard salad dressings

Six samples of non-standard salad dressing, containing 0.10 to 0.60% polysorbate 60, were submitted to 6 collaborators. The salad dressing is extracted and the extract is saponified and acidified, and the acids are removed. The aqueous, polyol solution is desalted and the polyoxyethylated polyols are precipitated as a highly insoluble heteropoly acid complex. The polysorbate 60 content is calculated from the weight of the precipitate, using a gravimetric factor. Average recoveries from the collaboration samples ranged from 105 to 130%, with standard deviations from 0.016 to 0.047. The method has been adopted as official first action.