By Frank on Wednesday, June 25, 2003 - 05:49 am:
I'm trying to develop a GC-method with a EPC PTV-inlet in solvent vent mode. Standard is dissolved in t-butyl methyl ether.
How to start; there are a lot of variables like:
injection temp. ,vent flow, vent press, ramp rate of PTV.
Using a Agilent 6890N GC and 5973N MSD
By ralph on Wednesday, June 25, 2003 - 11:22 am:
Frank,
Is this large volume injection with a packed bed liner? If so who is the manufacturer of the PTV?
Regards,
Ralph
By Frank on Thursday, June 26, 2003 - 01:47 am:
I use the Agilent 6890 PTV inlet, with a 1.5 mm I.D. 150 ul volume deactivated multi baffle PTV liner.
By Ralph on Thursday, June 26, 2003 - 09:24 am:
Frank,
Unfortunately I am not familiar with this one but I am sure Agilent would be very glad to help you set up a protocol.
If it is for large volume injection a possible protocol would be:
1. Inject 1uL of standard using on-column - this gives you the maximum value for comparison.
2. Fit your liner and inject 1uL of standard in cold splitless mode. Compare with the reference in (1) above. If the peak areas are smaller this indicates that some optimisation of your injector upper temp or splitless time is required
3. Set your injector to 30-40°C below the solvent bp, set the vent flow to(100ml/min? - I'm not sure with this design)and column temp to 20°C above your injector temp. Inject the volume of solvent that you intend to use using a vent time of 60 sec (again I'm guessing). Check the peak width of the solvent and adjust the vent time until you have a reasonable solvent peak width.
4. Now dilute your standard by a factor equal to the number of uL to be used in the LVI. Inject using the conditions in (3) and compare result with your original reference (1).
5. Fine tune - if you are losing volatiles reduce the vent time in small increments.
This protocol is "lifted " from the Optic PTV manual.
Regards,
Ralph
By frank on Friday, June 27, 2003 - 12:36 am:
Ralph,
I think you gave me a lot of helpfull hints.
Thanks,
Frank