Features:

Quality control

25th September, 2007

Fuels and fuel additives manufactured or imported in the US are subjected to strict regulations set out by the US Environmental Protection Agency (EPA). Biodiesel is the only alternative fuel to be legally registered with the US EPA and to have fully completed the health effects testing requirements of the 1990 Clean Air Act Amendments. Furthermore, pure biodiesel (B100) has been designated as an alternative fuel by the Department of Energy (DOE) and the US Department of Transportation (DOT).

In order for biodiesel to be sold as a fuel or blending stock, it must meet a set of requirements defined in ASTM D6751 and EN 14214, which specify the maximum allowable concentrations of contaminants in B100 finished products. Biodiesel must be produced to these strict specifications in order to ensure optimum engine performance as well as safe operation. Additionally, testing laboratories and regulatory agents must ensure that the labelled blend levels are present exactly as stated.

Effective testing of biodiesels is essential to identify compound types and values. US-based analytical equipment supplier Thermo Fisher Scientific provides a wide range of complementary analytical techniques for the quality control of biodiesel and the identification of labelled blend levels. These solutions comprise a variety of techniques including gas chromatography (GC), infrared spectrometry (IR), liquid chromatography/mass spectrometry (LC/MS) and inductively coupled plasma spectroscopy (ICP).

Gas chromatography

GC analysis is a reliable and effective method for the quality assurance of biodiesel. The technique comprises a range of variations that respond to differing ASTM methods.

As specified in ASTM specification D6751, biodiesel should not contain a level of total glycerin which exceeds 0.25%. Glycerin reflects the quality of biodiesel: low levels of total glycerin ensure high conversion of the oil, while high levels of glycerin and glycerides can cause injector deposits, clogged fuelling systems and can affect cold weather operation. It is also necessary to monitor residual methanol in B100 blends, since even small amounts of this material can reduce the flash point (the temperature at which the fuel will produce a flammable mixture). Moreover, residual methanol can affect fuel pumps, seals and elastomers and can result in poor combustion properties.

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