Retention factor coupled columns

The actual determination of which factors are most Important In determining the accuracy of calculated retention will require further Investigation. The fact remains, however, that the developed approach and corresponding computer programs can predict retention under complicated experimental conditions with acceptable accuracy. The program as written can accommodate up to 6 coupled columns, each with their own particular k vs mobile phase composition function, over any desired gradient function. This represents then a nearly universal approach to the calculation of retention for solutes under all possible elution conditions. 

Fig. 2 Schematic of two chromatographic columns coupled in series. - mobile-phase flow, mobile-phase hold-up time, % retention time, k - retention factor, T- temperature, L - column length, r - column inner diameter, u - mobile-phase-flow rate, P - column phase ratio, R - column pneumatic resistance, R - pneumatic resistance, D - detector.

The retention factor of a solute in a coupled column series, can, for equal column temperatures... 

Coupling two (or more) columns in series makes a longer separation system. However, one should be aware of the fact that if a good column is connected with a mediocre column, the plate numbers cannot be added. If the retention factor is equal in both the columns, the total plate number is... 

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