BS EN ISO 6975:2005

What is ISO 6975 - Extended analysis of components of natural gas using the Gas chromatographic method about?   

ISO 6975 describes the specifications for the quantitative analysis of the following components of natural gas: helium, hydrogen, argon, oxygen, nitrogen, carbon dioxide, saturated hydrocarbons from C1 to C5, hydrocarbon fractions from C6 upwards, and aromatic compounds as benzene and toluene.  
It is not possible to make unambiguous identifications of hydrocarbons above C6. Even where “spiking” a gas mixture with known components shows where they elute, it cannot be stated with certainty that such a component is the only one with that retention time. Unidentified components are classified according to the carbon number which the analysis indicates to be appropriate. While this is a necessary simplification, it does allow a reasonable quantitative value to be obtained.  
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