by
BG » Fri May 27, 2005 9:53 am
Hello (bis),
pulse split is injection where you can divide the sample quantity (for hight concentrations). If you put 1 ml/min in your column and 50 ml/min in split line , you split at 1/50 your sample (1/50 go to the column and 49/50 to the split vent approximatively)
The pulse is a solution in split mode (why not !), when you have large sample volume or large expansion volume due to your solvant vaporiastion, to compress your sample and force it when it's vaporised to stay in the liner volume and limit the backflush.
For example when you make a pulse inj the system ask you
initial pressure pulse ( for ex. 10 psi)
time pressure pulse (0.15 min)
For a pressure column of 5 psi (for ex.)
The system, after the inj. , increase the pressure to 10 psi to compress the sample vapors in liner and after 0,15min come back to 5 psi for the separation processus in the column.
Splitless is an injection mode to reconcentrate the sample (few 10ppm to few 10 ppb).......including impureties !!! (see your pb of parasite at start of your chromato....)
In this mode during splitless time you trap sample in column head by cold trapping ( split line is closed during this time)and after you re-open the split line to evacuate a large part of the "solvant queue", and in the same time (most of time ) you start the temperature programation (whith hight temperat rise !)
Don't be
, i hope i've ben clear !!
good luck
