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Determination of antioxidants by ion chromatographic analysisThe Antioxidants vitamin E and Baynox®
Quality monitoring The oxidation stability of fatty acids and of the fatty acid methyl esters synthesized from them can be improved by the addition of antioxidants. Biodiesel based on rapeseed oil already contains an outstanding natural protection against oxidation – vitamin E (d-a-tocopherol). In addition, Baynox®, whose structure was inspired by that of vitamin E, is added to the biodiesel as a stabilizer. This inhibits both oxidation to corrosive acids and the formation of insoluble polymers and thus prevents the injection nozzles from being blocked. Both these substances are therefore determined within the context of quality monitoring and for determining the amounts of additives to be added. Antioxidant analysis Because of their structural similarities, vitamin E and Baynox® can be determined together in a single analysis. To improve solubility, dichloromethane is added to the eluent and analyte solutions. The biofuel samples should be diluted 1:1000. The analytes are separated at 35 °C and then determined quantitatively using UV detection. Ion chromatography by Metrohm For the determination of antioxidants for quality assurance purposes, Metrohm recommends the 844 UV/VIS Compact IC with built-in column heating. This unique instrument in the ion chromatography sector combines the advantages of a compact IC system with a diode array detector (DAD) in a single housing. The method can be completely automated by combination with the 838 Advanced Sample Processor. This saves both processing time and costs. Product information 844 UV/VIS Compact IC with built-in column heating (including IC Net software) |
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