The Metrohm 743 Rancimat is a modern, PC-controlled analytical instrument for the comfortable determination of the oxidation stability of Biodiesel (fatty acid methyl esters, FAME).

In addition to other alternative fuels such as ethanol, methanol or biogas (methane), fatty acid methyl esters are increasingly being found on the market; these are also known as biodiesel or FAME (fatty acid methyl esters).

Fatty acid methyl esters are relatively unstable on storage, as like all natural oils and fats they are slowly oxidized by atmospheric oxygen. The substances produced in this way could cause motor damage. This is why the oxidation stability is an important quality criterion for biodiesel; it is regularly determined during the production process. The use of alternative fuels from renewable vegetable sources has become increasingly widespread in recent years, as the life cycle of biogenic fuels is neutral with respect to CO₂ release. The carbon dioxide released has already been assimilated from the atmosphere during plant growth. In contrast to fossil fuels, biogenic fuels neither contribute to the accumulation of CO₂ in the atmosphere nor to global warming. In addition, alternative fuels are biodegradable and thus less environmentally harmful.

The oxidation stability of fatty acid methyl esters has already been included in various test methods as a standard parameter used to define the minimum quality requirements of biodiesel: .

• EN 14214 <Automotive fuels - Fatty acid methyl esters (FAME) for diesel engines - Requirements and test methods>.
• EN 14112 <Fat and oil derivatives - Fatty acid methyl esters (FAME) - Determination of oxidation stability (accelerated oxidation test)>