Naturally occurring fats, oils, and waxes are known as simple lipids. When simple lipids oxidise, lipid peroxides are produced, often creating a rancid smell and taste. The detection of peroxide is a common indicator of the freshness of these simple lipids. It gives a measurement of how much primary oxidation has taken place. Peroxide value is defined as the amount of oxygen per kilogram of the simple lipid. The units for peroxide value are usually expressed as meq/kg (milli equivalence per kilogram). The testing for peroxides is performed as part of quality control in cosmetics, foods, and many other applications.
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.
The customer appreciated that the HI902C had a USB connection for both a PC and a flash drive. Both of these features make it very easy to transfer reports from the meter to a PC for record keeping and review. The customer also liked that the HI902C could be used as a laboratory pH meter, saving additional cost and space.
Download Titration Catalog: