Frontal Analysis:

Within frontal analysis, a huge sample in a suitable solvent is passed by a short adsorption column previously saturated along with solvent and the effluent is analyzed continuously until its composition is identical with that of the original sample. Consider a three component mixture containing equal quantities of each component fed continuously onto a column. Since, of the forces among solute and stationary phase, each solute will be retained to a different extent as it comes into equilibrium with the stationary phase while passing through the column. The first component to elute will be that which is held least strongly in the stationary phase, then the second component will elute but in conjunction with the first component, and finally, the most strongly held of the three will elute in conjunction with the first and second components. Subsequently, there will be no change in concentration of solute in the mobile phase and the concentration of the respective solutes will be the same as the feed mixture. A concentration profile resulting from frontal analysis is shown in Figure (a). The continuous curve shows the total concentration of solutes in the eluent, plotted against volume of mobile phase passed through the column, and the dotted curves represent a similar concentration profile but for each individual component. Frontal analysis was employed as a development procedure in the early stages of chromatography and before detection procedures were fully effective. It is not often used today, and certainly not for quantitative analysis. The reason for this is that no individual component is completely separated from the others in the mixture.