MMI LVI Liner choice

[Karen01]

I am new to the Agilent Multi-Mode inlet , PTV inlets and large volume injection in general.

I have a splitless method that injects 1 uL of sample after a 40 fold concentration step. I want to do a 50 uL LVI injection skipping the external drydown step using the Agilent MMI in solvent vent mode.

Can I use the same single taper (without any glass wool) 900 uL splitless liner for the LVI injection as I used for the 1 uL injection or would I need a different type?

After reading the MMI docs and tutorial it's not clear to me.

- Karen

[Peter Apps]

Hi Karen

The simple answer is no, unless you do some fancy slow injections that allow the solvent to evaporate as you inject. These have their own problems. If you are injecting all at once then the liner has to be able to hold the liquid without any of it trickling out of the bottom. This requires a high porosity packing that holds the liquid by capillary attraction while still allowing the carrier gas to flow through. My experience is that the loose pack volume of the packing needs to be about ten times the volume of the liquid. You might be able to use a large plug of glass wool, and some of the liner manufacturers do liners with loose packings of e.g. diatomaceous earths. SGE do (did ?) a liner with a sintered filling with a hole running down through the centre. I tried these briefly and they look very promising (a slightly cruder geometry is the basis for a countercurrent "solvent effect" sampler that provides excellent repeatability). You may run into problems of adsorptive activity with the extra quantities of inlet packings.

Peter

[AICMM]

Karen01,

You might want to look at Gerstel's web site for more info on LVI. While it is not Agilent (thus not your version) they had a good selection of technical info on LVI. Then I would go to Agilent and grill them as well. I am pretty sure you will have to look at a different liner to make this work and it will only work (well) with a decent difference in bp of the solvent vs. the analytes of interest.

Best regards,

AICMM

[aldehyde]

http://www.chem.agilent.com/Library/use ... -90020.pdf

Here is a tutorial that may help you, I have limited experience with LVI/MMI. I've worked on systems that had it, but haven't run a lot of samples myself or anything. The ALS does have different injection speeds, but the speeds are limited to just slow/fast/faster I think. It supports up to 1 mL so 50 uL shouldn't be too tough.

If you already have the hardware I would just start by experimenting with very clean test samples. Figure out the setup and running the software with something easy. Use Agilent's test method and if you have any problems like the sample getting up into the lines it would pretty much be pure solvent and easily removed.

http://alexandria.tue.nl/repository/fre ... 617570.pdf

This paper references liners that contain a more solid frit or a cup to capture the liquid, could be helpful. Although I would think the standard split liner with wool would have enough surface to capture 50 uL, and it has a small glass bump on the bottom that gives it a bit more room above the gold seal in order to accommodate more flow.