Chromatography Forum

I am separating two enantiomers on a ChiralPak IA column using a 95:5 n-hexane/2PrOH mixture under isocratic conditions and a flow rate of 1 mL/min.

Enantioselectivity is good although I am botherd by the long analysis time (the peaks elute at 16 and 19 min respectively). Since I am new in chiral chromatography I would be most grateful on advice on how to greatly shorten the analysis time. Increase the amount of 2PrOH? Apply a gradient? Add a modifier?

Thanks so much in advance!

Try increasing the iPrOH in 1% increments and see what happens. That should decrease retention times but it will probably decrease your resolution a bit. You'll have to experiment to see what the best trade-off is.

The other possibility is to increase the flow rate. Check with the column vendor to make sure there are no column stability problems first; if not, then increase the flow rate as high as you can go consistent with your paranoia about pressure and the effect on baseline noise. As with increasing iPrOH, you will lose some resolution in the process.