AI Article Synopsis
- - The EN 14105:2011-07 standard outlines a gas chromatography method to measure impurities like free glycerol and various glycerides in biodiesel, using an "on-column injector" for sample introduction.
- - While the "cool on-column" (COC) method is precise for measuring triacylglycerides, it has issues like band broadening and reduced robustness over repeated injections.
- - A study found that a "temperature programmable split/splitless" (TPSS) inlet performs equally well as the COC method for concentration measurements, but with better reliability and improved focus for early eluting compounds.
Article Abstract
The European Standard EN 14105:2011-07 is an analysis method for quantifying free glycerol and residual mono-, di- and triacylglycerides impurities in biodiesel by gas chromatography. The method specifies an "on-column injector or equivalent device" as the means of sample introduction. Cool on-column (COC) would appear to be an ideal choice, particularly for quantifying triacylglycerides, as it provides high quantitative accuracy and precision with minimal mass discrimination. However, there are a few drawbacks in using COC for this application. The relatively high concentration of the biodiesel in the prepared samples impedes solvent focusing of early eluting compounds such as glycerol, causing band broadening and shifts in retention time compared with the external calibration standards. More problematic is method robustness when using a metal retention gap. Repeated injections onto the retention gap cause the method control specification to fail within relatively few injections. As an alternative, a temperature programmable split/splitless (TPSS) inlet was investigated for performance equivalency. The results demonstrate that the TPSS yields concentration measurements indistinguishable from the COC inlet at the 95% confidence level. In addition, the robustness of the TPSS far exceeds that of the COC inlet by eliminating the performance control failure and providing solvent focusing for the early eluting peaks.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4890458 | PMC |
| http://dx.doi.org/10.1093/chromsci/bmw015 | DOI Listing |
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