Chromatography Forum

Hello,
this may sound a little strange, but I'd like to know if it's possible to "trick" Varian's Star Ver. 6.41 software (controling an LC) into starting a single acquisition without actually injecting. I hope to infuse the relatively large sample volume (~5mL) through one of the buffer/solvent lines as I don't have (yet....) a large volume injector available. If I didn't want to record the data from the detector (ProStar 325 module) then I could use the pump (ProStar 240 module) under local control and collect fractions (something I intend to do anyway). However, I need the data from the LC detector too, which is point that I can't progress beyond. So, is it possible to use the kit detailed above to do a single analysis in the normal way with the exception that there is no actual injection?
Thanks,
Dan.

Hi Dan,

I would suggest simply disconnecting the pump tube from the injector and connecting directly to your column or large injector or detector, then let the autosampler think it is making its injection even though it is not connected. I'm not sure how the Varian autosampler works but you might try simply putting a 5 mL volume of large bore peek tubing on the autosampler injector. You would have to load this loop manually but the autosampler might then start the run for you.

I don't know if your system support it. You may start data acquisition after "filled" column as blank run (without injection).
... probably stupid answer ...

1) why would you bypass the injector?
maybe you can make a 0 µl injection and leave it inline or bypass it by connecting the pump direct to the column. If you bypass it, you can let him just normal injections done

2) in either way, maybe you can go with a chromatogramm which has some time shift on it.
Then maybe you can programm a gradient, where you run isocratically on initial conditions for a short time, then switch to the "sample line" for a desired time and if it's all done, back to the initial condition "starting" your method.

I think by this, you can trick the system but you will have to re-calculate the time axxis on your chrom (for this I think the initial step makes thing easier, maybe not).
Also think of the gradient delay volume (point of mixing - column head)

I hope the description is +/- clear...

Example (B=sample, initial cond: 100A)
t A B
0 100 0
1 0 100 (immediate change, or linear 0.9->1.0)
6 100 0 (immediate change, or linear 5.9->6.0)
...your gradient (without solvent line B )