Use of electron capture gas chromatography for the analysis of aromatic hydrocarbons. Part of a coordinated programme on the use of electron capture gas chromatography in organic analysis

In a systematic study for the detection of aromatic hydrocarbons with electron capture detector it was found that benzene and monoalkyl benzens give weak signals; penta-, hexamethyl-benzenes, biphenyl, and naphthalenes exhibit medium responses; and poly-nuclear aromatics, diphenylethylenes, diphenylacetylene and azulene show high signals of response. The temperature dependence of the equilibrium constant of electron absorption and desorption reactions can be used to determine the electron affinities of compounds exhibiting medium or high responses. The EA values for 39 aromatic hydrocarbons were found in the order of 0.07 to 0.6 eV. It was also found that the rates of electron absorption increases with increased electron affinity of the molecules, whilst the rates for desorption of electron decrease for molecules with stronger electron affinity