Determination of Free and Total Glycerine and mono-, di-, triglyceride content in B-100 Biodiesel Methyl Esters according to EN 14105

IntroductionEN 14105

The European Standard method, EN-14105, is used to determine the free glycerol and residual mono-, di- and triglyceride contents in fatty acid methyl esters (FAME) typically intended for addition to mineral oils. Total glycerol content is calculated from the results obtained. The method is suitable for FAME from rapeseed, sunflower and soybean oils, but is not suitable for FAME produced from or containing coconut and palm kernel oils due of the problem of peak overlapping. This method and ASTM D6584 are two of the most used standardized analytical methods used for the analysis of biodiesel.


Fig. 1 – Biodiesel Chromatogram

Experimental

The SCION Biodiesel analyser for EN 14105 is based on our 8300 GC platform, a cold-on-column injector, a SCION-Glycerides Inert Steel analytical column with a 2m retention gap and a High-Temp FID Detector. Analytical conditions for the EN 14105 analysis can be found in table 1.

Injector Cold-on-Column
Column 10m x 0.32mm x 0.10μm

SCION-Glycerides Inert Steel

(SC38613)

w/ Ret. Gap
Oven Program Start @ 50°C (1 min)

15°C/min to 180°C

7°C/min to 230°C

10°C/min to 370°C

End @ 370°C hold 10 min.
Carrier Helium @ 80 kPa
Detector FID @ 380°C
Inj. Volume 1µl
Software Compass CDS

Table 1. Analytical conditions

Sample Preparation

Calibration mixtures and internal standard solutions were prepared according to the method.100 mg of homogenized sample was accurately weighed in a 10 mL vial. Then, using a glass syringe, the following was added to the vial: 10μL of internal standard No. 1 stock solution, 100 μL of internal standard No. 2 stock solution and 100μL of MSTFA. Care was taken to ensure there was no contact with moisture. The vials were hermetically sealed and shaken vigorously. After storing the vials at room temperature for ~ 15 minutes, 8 mL of heptane was added to each. Then, 1 μL of the reaction mixture was automatically injected into the gas chromatograph according to the instrumental conditions described below (see Table 2 for typical results).

Index Name Area (µV.min) Quantity (%m/m)
1 Monoglycerides 5692,9 0,69191
2 Diglycerides 758,0 0,06116
3 Triglycerides 714,6 0,06234
4 Glycerin 199,8 0,00975
Total 7365,3 0,82515

Table 2. Typical results for B-100 Biodiesel

Results

Calibration curves were obtained for glycerin, monoolein, diolein and triolein. Calibration curves for glycerin and monoolein, shown in Figures 2 and 3, are indicative of system performance for the application.


Fig. 2 Biodiesel calibration 001 Glycerin


Fig. 3 Biodiesel calibration 001 Monoolein

File Glycerin (% m/m) Monoglycerides (% m/m) Diglycerides (% m/m) Triglycerides (% m/m) Totals
1 0,00975 0,69191 0,06116 0,06234 0,82515
2 0,00976 0,71111 0,06304 0,06063 0,84455
3 0,00988 0,68955 0,06491 0,06175 0,82618
4 0,00977 0,67079 0,06429 0,06165 0,80650
5 0,00984 0,67629 0,06290 0,05548 0,80451
6 0,00985 0,68240 0,06629 0,05770 0,81624
7 0,00980 0,69243 0,06236 0,06057 0,82514
8 0,01012 0,60468 0,06489 0,06096 0,74065
9 0,00982 0,73039 0,06448 0,06212 0,86680
10 0,01014 0,72353 0,06282 0,05948 0,85597
Average 0,009883 0,687308 0,0663714 0,060268 0,82117
STDEV 0,00015 0,03501 0,00151 0,00218 0,03480
STDEV (%) 1,5 5,1 2,4 3,6 4,2

Table 3. Repeatability results for B-100 Biodiesel

Conclusion

This application note demonstrates the suitability of SCION Instruments Analyser for EN 14105, for the analysis of biodiesel. The calibration curves and repeatability data demonstrate good system integrity. Therefore, the system is well suited to the analysis of free and total glycerol and mono, di and triglyceride content in biodiesel in accordance with the standard method EN 14105.

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