Although a tentative structure for peak X has been proposed, it has yet to be confirmed by an independent laboratory. We really are not yet sure just what peak X is. All nutrients and drugs, whether they are FDA-approved or not, have impurity peaks, some of which are identified and many of which are unknown. It has an injection port at one end of the tube and a detector at the other end. As the sample flows down the tube, the different molecules separate from each other depending on their affinity for the matrix packing.
Slippery molecules flow through the matrix rapidly and are the first to emerge.
Sticky molecules are slowed down as they pass through the packing and are delayed. At the far end of the tube, a detector measures the separated chemicals as they emerge, producing peaks on the graph paper. The exact profile of peaks not only depends on the injected sample, but on the choice of packing material, its particle size, the solvent or gas mixture used, the flow rate, the temperature, the pH and many other factors. Often, chemicals with entirely different chemical structures can have similar or identical affinity for a particular packing. This can cause peaks to blend into or superimpose on each other.