The test mixture consisted of
six compounds (see Fig. 1). Fig. 2A shows a chromatogram of the
vanillin test mixture using the methanol–water mobile phase (25%
methanol in water with 0.2% acetic acid) that yielded the best separation
on the BDS C18 column at ambient temperature. Fig. 2B
shows a chromatogram of the same test mixture on a butanol water