Getting my run over with!

[MichaelVW]

I have a 6890/5975 with a Performance Turbo pump. Column is RTX-5MS (30m x 0.25 mm ID 0.25 um df).

Here's the deal. I have a 35 minute run that works great, but 90% of the time I'm only interested in compounds that come out in the first 11 minutes. So quite often I'm just twiddling my thumbs for 20 minutes.

I don't want to make a whole new method from scratch that analyzes for just those early analytes. I am hoping I can copy my method, leave everything the same up until the 12 minute mark, and then have the oven ramp rate and flow rate increase to get everything out of the column quicker.

Can I do this? Is it as simple as programming the ramp and flow rates to increase? Time saved here would be valuable but not if there's going to be any serious downside (the source getting dirty significantly faster, for example). The instrument manual says the preformance turbo can handle up to 6.5 ml/min. The max column temperature is 350. Am I ok as long as I stay under these values?

Any suggestions for me?

[James_Ball]

It is as simple as taking the method you have now and saving it to a new name then altering the ramps. Max temperature ramp should be 40C/min. Just add that ramp rate to start just as your last target elutes and program a hold at max for a couple minutes to make sure everything is off. You shouldn't need to increase column flow.

It can lead to cleaning more often but only because you will be injecting more samples in the same period of time. Should still clean as often as normal on a per sample basis.

Just be sure to save the method to a new name before editing, that way you won't accidentally overwrite what you have. I have learned that one the hard way more than once

[MichaelVW]

Thanks James. I've tried it out with just the temperature ramp and no changes to the flow rate. I checked to see how long it would take to get everything off the column so I won't have carryover: I shaved off about ten minutes from my run. I'd still like to cut that time down more with the flow rate if that's okay to do and doesn't have a downside. Anyone know?