A cosmetic company approached Hanna looking for a way to measure the peroxides in their products. An ASTM standard was used to develop a method for the HI902C potentiometric automatic titrator. A number of different solvent and sample preparations were tested to determine the most effective way of determining the peroxide value in the cosmetic sample. Ultimately, the recommended method involved dissolution of the sample in a mixture of toluene and isopropyl alcohol, followed by heating with glacial acetic acid. The sample digestate was then pretreated with potassium iodide. Sodium thiosulfate was then used as a titrant and the end point determined with the HI3131B ORP electrode. The results were accurate and repeatable, giving the customer a greater knowledge of the quality of their product.