7/27/2019 Infrared Spectroscopy of FAME in Biodiesel Following DIN 14078

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Application Note

Infrared Spectroscopy of FAME inBiodiesel following DIN 14078

Quantif ication of Ester FAME- in Biodiesel Blends

European agriculture produces a lot of plantscontaining oil which will be used forcommercial purposes. For the food marketthe rape seed oil is used as salad oil or asmain part of margarine.

Actual the rapeseed oil is also a discussionpoint for the biodiesel aspects.The quality of such biofuel and the blends ofit are controlled by the Biodiesel regulation.One aspect of the control is the FAME (Fattyacid methyl ester) contents.

Fig. 1: Transesterification of tri-glycerides toFAME

Biodiesel like rape seed oil is rich on fatmolecules which are treated in atransesterification process to contain a varietyof esters. The tranesterification is necessarybecause motors cannot run with the naturalrape seed oil which is too viscose.In the figure1 the chemical treatment is

shown in a short graph. The huge molecule ofa tri-glycerol is cracked into the glycerinemolecule and diverse FAME.

The blends of the biofuel are important to becontrolled. This is possible with infraredspectroscopy. The reason is the simpleidentification of the mixtures. In the figure 2the infrared spectrum of a mineral oil and abiodiesel are presented. The most importantsignal the ester related carbonyl bond atapprox. 1745cm-1 is quantified in the mannerto classify the blend of mineral oil and

biodiesel. This part is regulated by the DINEN 14078 norm.

50075010001250150017502000250030003500400045001/cm

0

0.1

0.2

0.3

Abs

Rapeseed biodiesel

50075010001250150017502000250030003500400045001/cm

0

0.1

0.2

0.3

Abs

Mineraloil source unknown

Fig. 2: Comparsion of Biodiesel and mineraloil significant difference is to see in theester signal at 1750cm-1

Content of DIN EN 14078The ester -CO signal is target of DIN EN14078 from March 2004 and has the titleLiquid petroleum products -Determination offatty acid methyl esters (FAME) in middledistillates- infrared spectroscopy method

The norm will focus on themeasurement range of 1670 to1820cm-1 and the signal of interest isat about 1745cm-1.

A cell with a thickness of 0.5mm andwindows prepared from KBr, NaCl orCaF2 should be used.

For dilution and cleaning the solventcyclohexane is to use.

A calibration is to establish with1,2,4,6 and 10g/l of FAME incyclohexane

Sample preparationIn this application a KBr flow cell from Specacwas used. The sample thickness was -as

defined from DIN EN 14078- 0.5 mm in

SCA_110_036 www.shimadzu.de

7/27/2019 Infrared Spectroscopy of FAME in Biodiesel Following DIN 14078

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