Analysis of Metals in Biodiesel Fuel

Standards are prescribed for fatty acid methyl esters (FAME) used as biodiesel fuels. The catalysts used in their manufacture contain sodium (Na) and potassium (K). High sodium and potassium content may result in the formation of solids or metal soap that can adhere to the engine fuel injectors or valves and cause blocked filters or other problems. Therefore, standards prescribe that the total sodium and potassium content of the FAME used as biodiesel fuel shall not exceed 5 mg/kg. This section introduces an example of the analysis of sodium and potassium in FAME manufactured from palm oil using flame atomic absorption spectrometry.
Results
The total content of the measured sodium and potassium did not exceed 5 mg/kg, meeting the requirements of the EN14214 specifications.

Atomic Absorption Spectrophotometer

A sample solution is sprayed by a nebulizer into a burner where it is heated and atomized. Hollow cathode lamps generate light at wavelengths inherent to the measured elements. This light is absorbed by the corresponding atoms, and the instrument measures the absorption of this light to quantify the target elements.