  Recently proposed new method "Ethanol as Internal Standard" for determination
of volatile compounds in alcohol products by gas chromatography (GC) is
investigated from different sides including method testing on prepared standard
solutions like cognac and brandy, different ethanol-water solutions and
certified reference material CRM LGC5100 Whisky-Congeners. Analysis of obtained
results of experimental study from four different laboratories shows that
relative bias between the experimentally measured concentrations calculated in
accordance with proposed method and the values of concentrations assigned
during the preparation by gravimetric method for all analyzed compounds does
not exceed 10 %. It is shown that relative response factors (RRF) between
analyzed volatile compounds and ethanol do not depend on time of analysis and
are constant for every model of GC. It is shown the possibility to use
predetermined RRF in daily practice of testing laboratories and to implement
this new method in the international standards of measurement procedure.
