Table 1.
Case | Mixture Sampleb | Mixture Type | 1tR, first | 1tR, last | 1 φ 0c | 1 φ find |
---|---|---|---|---|---|---|
1.e | A and B | Ideally retained | =1to | =1to+1tg | =0 | 3≤1φmaxi |
2.f | C | Weakly retained | >~1to | =1to+1tg | =0 | ≤ 1 φ max i |
3.g | D | Well retained | >1to | =1to+1tg | =0 | ≤ 1 φ max i |
4.h | Too strongly retained | ≥ 1to | >1to+1tg | =0 | ≤ 1 φ max i |
These are the conditions for optimizing the first dimension.
These are the mixture designators used in the text and calculation. Both mixtures A and B have a solute which elutes at 1to even when 1φo=0. The second solute in mixture A elutes at a time slightly larger than 1to whereas the second solute in mixture B elutes substantially later than 1to. Mixture C is the same as A but the un-retained component is missing and D is the same as B but again the un-retained component is missing.
It is assumed that the initial eluent composition is pure water. This is just a convenience for this work; any value could be substituted.
It is assumed that there will be an upper limit of 1φfin so as to avoid problems related to focusing the solutes in the second dimension. Any value would do.
In case 1 it is assumed that the solute set has a species which elutes at 1to even when 1φo=0 as well as a species that elutes at 1to+1tg even if 1φfin<0.8.
In case 2 we assume the presence of a very weakly retained solute which elutes close to or slightly later than 1to.
In case 3 we assume that the least retained solute elutes at a time greater than 1to given 1φo=0.0.
In case 4 we assume that the solute set contains a solute which is so strongly retained that it elutes later than 1to+1tg at 1φfin above the allowed limit.
1φmax, the maximum first dimension eluent composition, is 0.8 in this study.