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If one spot was in the middle of the plate and the other at the origin, the first spot could move the length of the plate while the second could only move one-half its length. Therefore, in this instance, they must move closer together.
options should be variants of this scenario.
must always move closer together. In practice, there is some diffusion that occurs. As described above, spots should become smaller and more defined as elution takes place. However, evaporation of solvent and diffusion (solvent movement doesn't move in a vector bottom to top path at a molecular level) also takes place and therefore, the longer or further a spot must move, the bigger it becomes from the small spot it started from.
result is that if you have two very well defined and small spots, rather then their becoming smaller and closer together, they will actually becomes larger and as a result appear to merge together if they are very close initially. If you did this with the spot in the middle, then the spot in the midde would be smaller and have less diffusion than the spot that began its travel from the origin.
diffusion is a reason that capillary GC columns have sharper peaks than large bore packed columns.
very small diameter reduces diffusion in a capillary column which results in peak broadening.
options should be variants of this scenario.
must always move closer together. In practice, there is some diffusion that occurs. As described above, spots should become smaller and more defined as elution takes place. However, evaporation of solvent and diffusion (solvent movement doesn't move in a vector bottom to top path at a molecular level) also takes place and therefore, the longer or further a spot must move, the bigger it becomes from the small spot it started from.
result is that if you have two very well defined and small spots, rather then their becoming smaller and closer together, they will actually becomes larger and as a result appear to merge together if they are very close initially. If you did this with the spot in the middle, then the spot in the midde would be smaller and have less diffusion than the spot that began its travel from the origin.
diffusion is a reason that capillary GC columns have sharper peaks than large bore packed columns.
very small diameter reduces diffusion in a capillary column which results in peak broadening.
Sun, 05 Feb 2012 18:03:56 GMT