Chromatography Forum

I regularly use the backflash calculator on Restek's website.
I have a 70mm x 2mm id liner and use methanol as sample solvent in a particular method. Therefore according to the backflash calculator I can only inject 0.1uL (and 0.2uL takes it over the liner volume).
My question is:
what effect does the split flow have on this calculation?
I use 100:1 at the moment - so to get more sample onto the column can I use 0.1uL and 50:1 or 30:1 etc?

Thanks in advance

WK

I didn't know about the calculator, but I consistenly have flashback on my septa

High temp, low temp...I always use single taper deactivated liners with or without the glasswool. If I run into a situation where carryover becomes an issue I will start to troubleshoot...but not until after the problem arises.

edit: flashback, duh

Hi WK

Vapour volume is really only an issue with splitless injections, when the liner needs to be big enough to contain the sample while it gets onto the column.

With split injections I wouldn't worry about it.

Peter

Agilent have a flow calculator...
http://www.chem.agilent.com/cag/servsup ... s/GCFC.htm

As mentioned by Peter, backflash is an issue only with splitless injection. If your are doing split injection, you could either reduce the split ratio or increase the injection volume to get more sample on the column. Normally the ratio should not be less than 10:1 as the control may become unstable.

If you are doing splitless injection using a split/splitless injector, the ratio change will not affect the amount of sample on the column. this is because injection port is isolated from the auxilary gas during the injection and all the sample is introduced to the column.