Retention correlation maps in comprehensive two-dimensional gas chromatography

A method of generating a retention index base for comprehensive two-dimensional gas chromatography (GC x GC) has been developed for the first and second axes of the two dimensional analysis space. The approach is described for an alkane base, and also with 2-methyl ketone and fatty acid methyl ester standards. The method involves repetitive, timed, sequential injections of the reference compound standard mixtures, and from the resultant data developing a retention correlation map. The first dimension generates linear temperature programmed indices, whilst the second dimension may be interpreted on the basis of 'pseudo isothermal' retention indices. From this map, retention information should be obtainable for any solute eluting within the allowed analysis region. It is proposed that this procedure will allow prediction of comprehensive two-dimensional gas chromatography (GC x GC) retention data or positions for compounds in the 2D separation space, and will also support development and understanding of rational column choices for GC x GC. The second dimension cannot be easily interpreted based on an alkane retention series, and so a more polar retention index base will be required.