A and B are single compounds containing two identical building blocks where as A-B and B-A represents positional isomers each containing two building blocks.

This analysis was conducted on the crude liquid-phase reaction mixture.  Each component contains multiple secondary and tertiary amine functionality yet the combinatorial products can be rapidly chromatographed and exhibit no tailing on a HAISIL HL C18 column using a simple linear 5 to 100% MeCN/water 0.1%TFA gradient.

Column: HAISIL C18 (High Load) 4.6x150mm  P/N: H LS-1546-C185

Higgins Analytical is grateful to Krishna Kalghatgi of NeoGenesis  for sharing these data.