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Standards Development
This European Standard specifies a gas chromatographic method for ethanol, in which higher alcohols (propan-1-ol, butan-1-ol, butan-2-ol, 2-methylpropan-1-ol (isobutanol), 2 methylbutan 1 ol, and 3 methylbutan 1 ol) from 0,1 % up to 2,5 % (m/m), methanol from 0,1 % up to 3 % (m/m) and other impurities, in the range from 0,1 % up to 2 % (m/m) are determined.
Impurities are all the compounds not attributed to the groups of higher alcohols or methanol.
Water, if present in the sample, is not included in this analysis, because a signal for water is not visible in the chromatogram. Therefore, if "alcohol content" is called up in a specification, water needs to be considered separately in the calculations.
EN 15721 is a method for the hydrocarbon analysis of denatured ethanol.
Ethanol blending component is sometimes located in a terminal where also petrol (or other common denaturants) is stored. It could be contaminated/denaturated with these components and when (independent) labs are requested to test the product they might not be aware of this. EN 15376 sets a limit of < 98.7% ethanol +high alc. by means of EN 15721.Ethanol that meets these requirements, i.e. max. 1.3% contaminated (on-spec), but with a contamination of petrol (allowed by EN 15376), may well be certified as approx. 2.6% of impurities using EN 15721 (offspec). This incorrect determination origins from the fact that all not mentioned impurities in EN 15721 shall be assigned a response factor of 2.
EN 15721 is for non-denatured ethanol and ethanol contaminants. These were originally considered to come from ethanol production only. Following experience with ethanol in the fuel logistic chain, WG 9 evaluated a recommended set of additional response factors for normal denaturants that labs can use in case of unintended contamination of the sample somewhere in the logistic chain. They suggested to require the use of self-defined RFs and present others as recommended.
The question was asked to WG21 whether this can be solved in EN 15376 or whether EN 15721 should be revised for slightly denatured or contaminated ethanol. The WG 21 convenor recalled that when the ethanol specification was drafted, the ethanol purity with denaturants was linked to the fact that all CEN members work with different denaturants, so it is difficult to find a common denominator. As companies still need to deliver proof to authorities and EN 15721 (being not suitable for all market situations) is used by controlling bodies, it was agreed that WG9 would check the feasibility of revising EN 15721 to deal with the case of fully denaturated ethanol and to include the response factor of the most commonly used denaturants. Such revision would make EN 15721 a more commonly applicable test method, especially for the independent labs or those that receive samples of which it is unknown whether they are denatured or not.
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