I have a good separation of a multi-substituted, cyclohexane that fully resolves ~12 different oligomers. I can detect the components by MS, but I would like to use a standard LC detector instead. There is virtually no adsorption above 230nm and below 230nm picks up solvent interference. I’m considering using RI detection and afterward subtracting a blank run. Is there any hope of this working or would I be wasting my time?

I think you would really be wasting your time with RI, gradients and RI do not go together. Have you considered an ELSD (evaporative light scattering detector) for this application? Fairly universal and works with gradients.

Yep, definitely a non starter. If you have absorption at 230nm, try using a mobile phase which is transparent at these wavelengths, what are using at present, is this 'normal phase?'
Can you derivatize?
Cheers
Bryan Wallwork

Thanks for the feedback. We have an ELSD in the budget, heopefully we can buy one. Changing mobile phases would be starting at the beginning again. That may be our only choice though.

Actually, we have budgeted for a multi angle laser light scattering (MALLS) detector. Is this close enough to the ELSD?

can anyone help me? I have an assignment to do for university I am studying my MSc and I need information on evaporative light scattering techniques eg. what it is? how it works? advantages and disadvantages? detection limits etc is there anyone that has any of this information?

Thanks in advance!!!

The MALLS detector is for polymer MW measurements in GPC. It is an entirely different animal than an ELSD, which is largely independent of MW. The MALLS detector requires a second detector for the dn/dc portion of the MW calculation, which is typically an RI detector, but since you will be using gradients, you'll need the ELS as well.