Minimum, analysis time, optimized column

Weyland et al. [560,561] used this method to optimize ternary mobile phase compositions for the separation of sulfonamides by RPLC. They fitted the retention surfaces to a quadratic model similar to eqn.(3.39), and also used a combination of a threshold resolution and minimum analysis time (min tm fl / vmin> 1.25 eqn.4.24) [560]. This criterion may yield a good optimum if the optimization is performed on the final analytical column (see table 4.11). 

Therefore we shall optimize the experimental conditions by looking for the minimum pressure at constant analysis time and efficiency for a given solute pair. It has been shown that this goal is accomplished when the column is operated at the optimum flowrate at which the plate height is minimum (19). The particle size and column length then depend on the plate number and the required analysis time. 

Figure 5 shows that here is a minimum in the analysis time at a separation ratio of about 1.06. Now, from the theory of analytical column design, It would be expected that, if the column was fully optimized, the analysis time would decrease continuously as the separation ratio of the critical pair increased. The reason that a minimum exists in figure 5 arises from the limitations place on the column by the minimum aspect ratio of unity and... 

For water- or air-cooled columns, the actual reflux ratio l actuai is normally 1.1 to 1.3 times the minimum reflux ratio The optimal relationship between factual and f niin can be established by an economic analysis that compares the cost of energy (which rises with rising reflux) with number of column trays (which declines with rising reflux). For the present example, assume that... 

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