DIRECT IMAGING OF THE STEPWISE ELUTION PROCESS IN HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

The migrating bands of solutes in a liquid chromatography glass column were directly monitored by a video imaging system, In the stepwise el ution mode, a rapid change of migration velocity of the solute band wa s observed when a second eluent just overtook the band, As a function of migration time and migration distance, the locus of each solute ban d showed two straight lines with a clear inflection point, It nas show n that the solvent front of the second eluent was kept sharp on passin g through the column, The inflection points of all bands showed linear correlation coefficients, This line of inflection points showed a loc us of the average solvent front of the second eluent and the slope of this line showed the linear now velocity of the eluent, A momentary co mpression of the bandwidth was also observed when the solvent front of the second eluent just passed through the solute band.