Parallel Chiral Column Screening

In chiral column screening, it is essential that the conditions for separating chiral substances are found quickly and effectively. As a result, many large pharmaceutical companies have recently decided to equip their chiral column screening departments with an 8x Sepmatix system. The 8x Sepmatix system for chiral column screening can separate a substance on eight different chiral separation columns simultaneously. This significantly increases sample throughput.

The system consists of three modules: an 8x FlowControl low-viscosity version with flow rates of between 0.25 to 1.50 ml/min; an autosampler with syringe pump which injects samples from standard microtiter plates or deep-well microtiter plates onto eight columns (also suitable for vial racks); and an 8x diode array detector
with eight analytical flow cells applicable for the spectral range of 200 to 600 nanometers. The required space for the 8x Sepmatix system for chiral column screening is only 55 x 55 x 90 centimeters (W x d x h). The 8x Sepmatix system for chiral column screening can be fitted with the Sepmatix EluentRack, which is designed for a maximum
of four solvent selection valves (each with six positions) and up to 24 solvent bottles (1 liter) or 18 fl asks (2.5 liters). the required space for the sepmatix eluentrack is 55 x 55 x 90 centimeters (W x d x h).

The parallel screening system shown above is assembled from the following modules:

HPLC Pump,Knauer
Solvent Selection Rack- 24 solvents, Sepiatec (right)
Sepmatix 8x FlowControl, Sepiatec (left)
Sepmatix 8x Autosampler, Sepiatec (left)
Sepmatix 8x DAD Detector, Sepiatec (left)
Sepmatix 8x Column Oven, 10-70 ° C, Sepiatec (left)

HPLC Conditions:

Flowrate: 1 ml/min per channel
Eluents: Hexane with different additives Ethanol, Methanol and Isopropanol
Detection: DAD 200-600 nm, online 210 nm
Injection: 5μl in each channel
Columns: 8x 250x4.6 mm

Settings for the Solvent Selection Rack

The solvent rack providing a selection of six solvents at each of the four low pressure gradient input valves of the pump gives the option to connect 24 different solvents to the system. To ease the process of the method programming first a table of all solvents is entered in the software. After setting the right solvent for each inlet, only the percentage per low pressure gradient inlet valve has to be set in the method.

Exchange of solvent can be done in less than one minute due to the fact that only the solvent in the short connections from the solvent selection valve to the pump has to be exchanged using the flowrate for eight channels.

Running coated and immobilized polysaccharide CSPs in the same system

Since coated CSPs would avoid the use of some solvents, the Sepmatix system allows switching off the channels with these columns for the runs with solvents that might damage the coated phases.

A valve integrated in the FlowControl unit completely blocks the flow for these channels and no damaging solvent reaches the coated columns. Valves for channels disabled in the Sample Table are colored yellow in the Online screen.

Security System for coated polysaccharide

To avoid damaging of coated polysaccharide columns the Sepmatix Control Software has a security system that allows defining damaging solvents for each column. With this information the software ensures that no damaging solvent can be used with a wrong column. If wrong solvents are chosen by the user, the software will not start the run to avoid any damages to the columns.

Purge setup to flush out traces of "damaging" solvents

To ensure that no traces of damaging solvents that might still be trapped in the FlowControl can reach the columns, an automatic purge is integrated to flush all the solvent out of the FlowControl. The necessity to flush is determined by the software without user interference.

Sepmatix 8xColumnSelector

To combine an interesting new idea like parallel screening with an established approach might even enhance the procedure further. In this case a set of column selectors is added to the parallel HPLC system. With this setup in each of the eight channels six different columns can be installed. This setup allows 48 different columns to be screened automatically without user intervention. This 48 columns can either have different CSPs or the same columns can be used in neutral, acid and basic mode.

Results

With the Chiral Column Screening Wizard Software it is possible to reprocess up to 80 chromatograms (10 sepmatix runs) in a few minutes. Visual inspection of the chromatograms shows the best separation on
Column 4 with the solvents used in Method 13. The resulting parameters from the integration are used to build up a hit list of separations.

Conclusions

With the upcoming of more stationary phases for the separation of chiral samples, enhancing the throughput of column screening is a key issue for a thorough test of possible combinations. With a parallel HPLC system the process can be speeded up. Thus the influence of other parameters and further solvents can also be investigated.