Biodiesel: Testing for Methanol Contamination

Because methanol is commonly used as the catalyst for the transesterification reaction during manufacturing, it may remain at residual levels in the final B100 biodiesel product. Too much methanol in a fuel will cause engine stress. Therefore, its level must be below set specifications for a fuel to be acceptable. DIN EN 14110 describes the headspace analysis of biodiesel for methanol, and is used to verify the residual methanol level is below set guidelines. A capillary GC column with a non-polar phase is most suitable for this application, allowing the more volatile compounds (analyte methanol and internal standard 2-propanol) to elute prior to the biodiesel components (FAMEs). Our Equity-1 columns are made with a poly(dimethylsiloxane) phase, which allows separation of analytes primarily according to boiling point. Several dimensions of this column are available to suit the needs and desires of the analyst.

As an alternative to traditional headspace, headspace solid phase microextraction (SPME) is also able to perform this application, requiring considerably less equilibration time (5 min. vs. 45 min.) while exhibiting excellent sensitivity at the low end of the required calibration range.

Whether by traditional headspace, or headspace SPME, we have many high-quality products for the determination of methanol in B100 biodiesel.