Tandem Operation

Short analysis times in the laboratory save valuable time. Running the Dionex UltiMate 3000 x2 Dual-Gradient HPLC System or Summit x2 Dual-Gradient HPLC System in tandem operation mode allows increasing the sample throughput considerably, typically by 50 to 100 %.

System Requirements for Tandem Operation

When performing tandem operations using an UltiMate 3000 x2 Dual-Gradient system, the instrument setup should be as follows:

• two gradient pumps with identical flow rate or one dual-gradient pump

• one TCC-3x00RS/SD, TCC-3100 or TCC-3200 comprising at least one 2-position 10-port switching valve

• one WPS-3000SL or WPS-3000RS/TXRS

• two columns

Operating Principle

For a gradient separation, it is usually necessary to wash and reequilibrate the column for the next run when the different analytes of a sample have been separated. During this time, the autosampler, detector, and fraction collector (if installed) are running idle. Analyzing the next sample during the wash and reequilibration steps can considerably enhance the productivity of these devices. Equilibration is performed offline.

The example illustrates that phases 2 and 3 could be performed for one sample. In parallel, phase 1 could be performed for the next sample, on the second pump and second column. This requires the following system configuration:

In position A (valve position 10_1), the chromatographic separation is performed on column 1. During this time, the wash and reequilibration steps are performed for column 2. When the valve is in position B (position 1_2), the separation is performed on column 2 while the washing and reequilibration steps are performed for column 1.

Using this configuration, you can considerably shorten the analysis time for the above example when you

• Stop the active gradient after 25 minutes.

• Set the solvent back to the starting composition (%B = 11%).

• Wash the remaining eluent out of the capillaries between the pump and the column switching valve, using this composition for 1 minute.

• After this minute, switch the valve to direct the flow to the second column and inject the next sample.

This considerably reduces the run cycle time and increases the system throughput, typically by 50% to 100%.

For more information, refer to How to …: Creating and Modifying Programs  Defining Tandem Gradients (UltiMate 3000 x2/Summit x2).