Chromatography Forum

Hi everyone:
I have an IC that is not used often. I am thinking to couple it to my mass spect. However, I am debating the necessity of doing so. I have some surfactant columns that have both RP and ion exchange functionalities. Will coupling the IC system to MS offer better separation than using only surfactant columns? Does anybody have experience on this topic? Thanks.

Several points to consider:

1. The separation per se is a function of the column and mobile phase chemistry. Coupling a MS to an IC system will affect detection.

2. The use of MS for detection imposes some serious constraints on what mobile phases you can use. Specifically, all components of the mobile phase (including buffers!) must be reasonably volatile.

3. "IC" is really just a subset of LC (generally, using conductivity detection). In principle, coupling a mass spec to an IC system is exactly the same as coupling it to an LC. The devil is in the details: MS detection generally requires flow rates that are low (and correspondingly small columns) by IC standards. If your system can handle the flow rates, and has sufficiently small extra-column volume, then it should work, but it probably won't be "plug and play"!

Dionex has a model made with a Thermo MS and I believe I have see ABSciex MS with Metrohm IC units interfaced.

The only difference in these versus a normal HPLC is that all of the flow path is constructed out of PEEK. This eliminates any metal contamination and interference for the conductivity detection. Also if you pass the mobile phase through a suppressor you should only have CO2 left from a carbonate mobile phase so it should be compatible.

As long as you use only carbonate, ammonia and hydroxide based mobile phases you should be ok on compatibility. I know our Metrohm IC operates at about 0.7ml/min so if you are running like that then flow shouldn't be an issue either.

Thanks for the tips. I am still hesitating if I should keep this IC unit. If I could couple it to the MS, then I may find it more useful for some ions that I don't see good separation with the current available LC columns.

I understand I will have to add organic post column to make it more compatible with the MS. As for the suppressor, should I purchase an external one? I know there is one in the IC instrument already before the eluent reaches the conductivity detector. Thanks again.--Jennifer

On some setups I have seen, you just let it pass through the conductivity detector and then into the mass spec, that way you get both results and no need for an extra suppressor.

Wow, that will be nice if I can run it without any extra purchasing!

Thanks!